I've spent a few days now tinkering myself to get things right as the first time I've played at modding myself. Its been a steep learning curve for sure, especially when most of the guides I find glossing over the detail that is actually key. Given how much time I've sunk, I've loaded a few videos of idiots guides to modding that will include liveries and race gear as well for this years game.
I too watch a fair few of the more well known content creators and their custom liveries, and this spurred me to give it a go despite being anything more than amateur idiot. That said, I think my first attempt looks on point
Playlist guide is here -
Rikadin's Idiot's guide to modding F1 2020