You can easily spend a few grand on lenses for a system (say Canon DSLR or Sony Mirrorless) which is a reason why, if you want to upgrade, you get a better body in the same system you already use.

I switched from Canon to Sony but that was because I lost my camera and only had one working lens at the time (believed back then a wide angle prime is all you need.). I didn’t know how I would make it w/o Canon USM lenses (which closely integrated manual and automatic focus) but I found nothing but complaints about the autofocus on Canon full frames unless you drop $6000 on a top of the line body.