Original Prusa Mk3 user

What is the optimal tolerance for fit parts into place?

For example i have an LCD that measures 100x50mm, in a perfect 3d printer i would cut a 100x50mm hole in model and LCD will fit like a glove, but instead it will not fit, thats the nature of 3d printing and plastic been used.

So what would be the best cut size for that example? Is 0.2mm for each side ok? So total margin is 0.4mm^2 (100.4 x 50.4mm)?

My objective is plastic hold the part itself without forcing or damage something, fit at best size, so i don’t want the part/lcd to be loose even if i will use screws.

Printing in ABS, PLA, and PETG would need different tolerances?

Also my target layer height is 0.30mm for large parts