@FoxtrotDelta and @Spitfire7 Sorry I joined the party late. I have read the entire thread found the vehicles.meta file which is located in Grand Theft Auto V\mods\update\update.rpf\common\data\levels\gta5
however, after adding these 3 lines
FLAG_IGNORE_RWINDOW_COLLISION
FLAG_DISABLE_THROUGH_WINDSCREEN
FLAG_HAS_BULLETPROOF_GLASS

to the flags it still did not achieve bulletproof glass. Am I doing something wrong? It is a modded car (added. not replaced) I am dealing with:
https://www.gta5-mods.com/vehicles/2018-rolls-royce-phantom-viii

I look forward to hearing from you. Thank you in advance.