@youngseasoon I will let you know in few weeks/months already working on it, graphic, architectures, props done, working on vehicles now. You can see more progress on instagram or discord linked bellow. But not every of vanilla vehicles have real life model already made.
You need gameconfig for sure.
You need a lot of backup and testing coz not every model is working. You need lot of time and really much much more patience than time sometimes I spend over 10 hours on one model to find perfect model (or almost perfect and unlocked) and fix all issues
You need to take care of rpf and dlclists sizes due to what @TRDOffroad97 mentioned coz in so many mods the game can easily get unplayable.
To keep mission working you need also more testing than I mentioned coz mods can work in normal story mode, but can affect missions and bug them.
You need have or be open to learn basics of meta files editing and zmodeler works coz soe models, especialy that not so popular as services vehicles or old vehicles have bugs in meta files, have not breakable glass, have no reflections in mirrors, have not hands on steering wheel etc. and all of that you need for gta as real as possible