Upgrading a7 III: IV, V, RV, RVI or just get a new lens 24-70mm f/2.8 GM II

Hi everyone, I'm a casual photographer. I like my A7 III, but I always regretted not buying IV (it came out one week after I bought III). I mostly do family photos, animals, and planes. I have two lenses: a 24-105 f/4 and a 100-400 GM. My shutter count is only 20k, but I absolutely love the photos I take from the trips, etc.

I want to upgrade something, but I want to make the most reasonable purchase. Help please