I think you’re already pretty good with photorealism, although, I like to add/change some few things, this is very personal preferences, so it doesn’t really matter if you don’t have that in your scene :
The first thing that I’ve noticed is the black cover, the brown thing, is it dust ? If yes, I would maybe lower the amount of it, when you look at the others places of the room, they don’t have that much dust.
I would add some slight dust in the air, it’s very suddle, but I think it can add some good atmosphere in your scene
I did also change a few colours variations, like having shadows being a slight dark blue (again, this is purely personal preference), adjusted the contrast and luminosity.
I’ve also added a very suddle god rays/lights rays (never know how they call this things)
And finally I’ve added a black frame, just to focus even more the attention on the scene
I’m not really good with the suggestions that you’ve mentioned because I think that’s towards the photography side(?) and I don’t really have experience it in lmao.
I’ll look through around those range of options for my future renders to see if I can make it better.
Some 3d artist, after their final render, they go with photoshop or something else (affinity photo in my case) and try to enhance their render even more, it’s called post-processing
I highly recommend you to try it as you have also free software that do just that