Aaaaah, guys....
The short answer is: I have to find specific practices and do them.
The obvious follow-up is: Which ones? (Besides mimicry)
You'd have to share videos for people to see specifically what you need to work on. The best people in any activity are either good at working this out for themselves, or they have a coach who observes them and gives them specific practices to do. For example, in swimming it's common for coaches to get swimmers to do "drills", which are movements that train an individual element of the stroke, as most people's brains can't cope with focusing on lots of things at the same time. An analogy in driving games would be to focus on just one element of one corner. For example, focus on getting the car position on entry spot on. It doesn't matter if this is mimicry, just copying the best driver in the world, so long as you understand why they are positioning the car where they are. An example would be the entry to the final corner at Nurburgring GP, where you see the top players just getting that little bit wider on entry than slower players. It would be nice if the game had a rewind feature to allow practising one element like this over and over again in isolation, as I find it really annoying to have to wait a couple of minutes in between each time I practice something like that.
The vast majority of what makes people slower than the best driver, is:
1. Not entering as wide as is possible
2. Not apexing as tight as is possible
3. Not exiting as wide as is possible
Most people are not able to replicate the exact same car position every time, so the more random they are, the more they have to bring the car in from those limits to get around the track cleanly. The only way to get better at accurately positioning the car is practise. Then there is
4. Not braking as late as possible
5. Not going as fast as possible at every point on the track
JSR Devon goes through two replays here, looking at why the slower driver is slower. The same differences are still there if you compare e.g. world 10th place vs world number 1, they just become smaller.