I'm using the IVAO model matching package in conjunction with some custom rule files that were posted by a YouTuber I sometimes watch, BritishAvGeek. If you search for him and "model matching" on YouTube you'll find everything you need.
The IVAO models are not very detailed, and the textures are low res, but right now it's the best option I've found for getting the maximum number of aircraft in MSFS 2020 when you're using VATSIM.