Well in ride3 there's no clutch so that solves/simplifies it there. I also use x for the rear brake in both games. In ride 3 it becomes progressively stronger the longer you hold it so i just kinda pump it a little, if i find i turned in late mostly, or soon you will lock the rear.
In motogp19 the rear brake is alot smoother and weak and is easy to just keep it pressed to help turn in better as it doesn't get any stronger the longer you hold it. It's a little bit of a crutch i find in this as it's so easy to use but it helps of course to use it.
It depends on each bike too, like some historic bikes have stronger rear brake or at least slide the rear more to the point where you can lose it or lose time from slipping at least.
Also ride3 i think has smoother controls and cam perspective than ride2, or ride1 at least, so its more manageable i feel.
In ride3 i use helmet view and tuckin which helps turn in i find, also it's alot cooler feel leaning into corners.
I'm used to holding the tuckin with circle most times and can still upshift with the triangle without letting go of the tuckin. And i use square for downshift which is fine for it as you need let go of tuckin while slowing down so.
But once I'm in the turn i keep tuckin again and can still press the x for a little rear brake turn in adjustment.
Same motogp19 except it's automatic tuckin.
For the clutch in motogp19 i can either use the left bumper on the ds4 for digital clutch or the right joystick up for analog. But then i need change the shift up down from the square and circle buttons to the shoulder buttons let's say.
Not easy i admit to get used to changed controls. But it's pretty damn cool. That's why i want to get the new underbelly attachment for the ds4, i think it be easier to shift with the middle finger on the bottom new buttons while using the right stick for clutch.
I hope the ds5 will have them as default or at least as an option too. In the meantime sometimes i just use the left bumper for clutch in motogp19, especially for the newer non historic motogp bikes as they are a handfull with no aids and from what i was told they don't use a clutch except at the start. But in that game you can still at least throttle blip even without using the clutch, but it's easy to use the left bumper too for digital clutch to match revs when downshifting, which you need cause you can lose the rear if not on torquey engine bikes like the ducati. Not so much on the older bikes.
Edit: so in ride3 in curves i mostly use tuckin, throttle with a little power oversteer, front brake to slow down of course but also to try trailbrake a little and rider position too with the left joystick to adjust my line leaning forward a little more if the front gets too light too to help turn in and sit back to brake and lean backward when powering out of curves to have more weight and grip on the back and then push the rider forward when almost out of the curve to help the front not go up too much. And downshift to help rear engine braking and turn in.
And I'll pump the rear brake if i see I'm coming in too fast and won't be able to slow down in time if not.
In motogp19 its almost same but i use the rear brake cause it's so easy and almost mandatory for turn in, at least in some historic bikes, not sure about all modern bikes, i haven't tried that many yet. I also use it to just slowdown faster before a curve.
Same for downshifting, it seems even more needed in that game to engine brake the rear to help turn in, again especially in some older bikes.
What's fun with the analog clutch is a little overrev powershifting by slipping the clutch a little.
And for smoother downshifting and throttle blip. And for faster smooth starts by slipping the clutch as i did always in real life too.
well anyone needs do that a little anyways right unless it's an automatic lol or i don't know newer bikes if they are clutchless.
Edit2: one thing i noticed in ride3 is when you are tucked in most times the bikes react more and better i find, not just for turn in, but also wheelie from throttling out of curves alot more, which i find cooler and challenging and real to me, and you need adjust your throttling to wheelie not too much, even if you are leaned forward. It seems like the game reversed the reaction you should get when tucked in or not, cause it seems you should wheelie less if tucked in, i don't know, but it's fine to me cause i use manual tuckin always and love the handling like that.
You can notice it easily at the start if you don't tuckin and lean forward the bike will rarely wheelie, but if tucked in it still might and you need control your throttling. I think that's more realistic too cause a high performance modern bike im pretty sure will still have enough power and light weight to wheelie if you punch it at the start.
In motogp19 they also seemed to have reversed some effects, when you lean forward for example, you accelerate alot less in high speed, compared to sitting up, which seems silly to me as you are in the wind of course sitting up.
Surprising mistakes unless i don't get it, i dont know.
Edit3 hehe. One thing that should be worth waiting for ride4 instead of getting 3 is the a.i. if it's more like motogp19 in ride4 it will be alot less annoying as they are not in the way as much as in ride3 and bumping into you. That gets old fast when it keeps happening. And they are more varied.
Also i really hate how in ride3 the ai is so much faster in a straight line accelerating and coming into turns unless you upgrade or have one of the higher spec bikes. And then they are so slow in the turn my god, and in your way. I wish you can select each opponent bike for a race like in Ac custom championship and maybe have balance of performance for them. I don't like the idea of upgrading to be similarly performing as the ai.
On BrandsHatch, after the 1st turn where the track dips alot and you can run on the curb too, the rear can get light and you can lean backward a little to help not slip the rear, i like that part hehe. My god I'm rambling ook hehe.
I have MXGP3, Ride 2 & MotoGP17, one day.. Rest assured I'm reading all the posts 
Set it correctly, retried, won, (once I readjusted all my braking points). Put difficulty back to Realistic, still won. I`m gonna give this game a proper go now, despite my 3 hours or so of utter pain, I really got into the handling, its a nice break from the hardcore stress of Rally, but only if both brakes are working !!! 
