Yeah really depends on what you are shooting. I do some setup work in my backyard similar to what Jan is showing and for sure I can use 24MP and get way more cool shots with an A9III then the 50MP A1.
That said ,there are a lot of times I'm cropping the crap out of my A1 images when not shooting in such a controlled environment. The A9III images may not hold up.
However, I had many sub-24MP cameras as my main camera over the years: 1DX, 1DXII, A9 and A9II. So I know I can work with 24MPs. But you do get used to using the cropping power of the 45+ MP cameras and sometimes it feels like it will be a challenge to step back.