So what did he sell you on then? Their only Nvidia (GeForce / RTX) G-Sync monitors are 1080p 25" - 27" and their only 1440p is the 34" Curved. FS2020 is going to run below 48fps on your system. So unless he sold you a chipped full Gsync monitor… You will have to turn off Gsync or it will flicker regardless.
This is a list of the majority (not all) of the G-Sync monitors that are 1 -144 variable refresh rate and 48 - 144. Not all the monitors are on this list, but ANY monitor will work with that RTX 3070 and FS2020. Even a cheap 60hz monitor from Office Depot.