I'm not expert and haven't watched his lap. But just Diamond the one time at Nord. Every other time is gold.
The "cheat"(that works for me) is to grab a higher gear than what Lewis seems to be doing. From T1, I'm braking and select 2nd gear. Nail the throttle out of the corner and short shirt to 3rd. I'm ahead of him thru the first sector.
When doing the 5th gear run after that, it seems like he's using hair-trigger lift off throttle, to steer the car for the fast sweepers. That's how I'm able to maintain speed.
Even after the big Karrussell, that run up the hill to the sharp left and then braking, I ever so slightly lift and I still carry lots of speed.
The last part of the track before the final straight, I barely steer the thing and just drive as straight as possible over the kerbs. Entering the double lefts before said back straight, I take my time and concentrate on exit speeds. For the right handers, I maintain patience on the throttle, as Lewis' top speed slows, helping me shave a tenth or so.
NGP and Suzuka, I just had to keep practicing with each attempt. Following his ghost and braking earlier once I anticipate his brake lights. The car has too much understeer to do exactly what he's doing.
Overall, what I'm saying is, I figure out the characteristics of the car, how it behaves and say, "Well, okay, you behave like this when I do that" and adjust my driving to how the car moves at each corner. Seriously.