I love Lego but tend to do most of the building for my son (11). He has enough bricks to start a shop! I bought a couple of huge organiser cases last year and sorted 99% of it. Now I'd probably need to add another 2 of the same to hold it all. He inherited his sister's collection and since he was little all the relatives know he's into Lego so each Christmas and birthday he'll get a half a dozen kits.
Mainly Star Wars or Lego City (police, construction etc) with the odd Minecraft and Marvel.
He'll play with the models a while, generally a week or two at least but then will generally dismantle them and build something from his imagination. I confess I felt lightly disappointed at first when he did that with the TIE fighter model I got him for 10th birthday and spent hours building, but far better that than a standard toy that's played with for 5 minutes and then left, to be eventually binned. We keep all the instruction books so have the option to rebuild anything. He now also has a literal small army of the minifigures!
He went through a phase of building interpretations of the big Star Wars ships like the imperial star destroyers, but we had to veto buying him the giant UCS sets!
Toward the back end of lockdown I treated myself to this one though:
https://www.lego.com/en-gb/product/nasa-apollo-11-lunar-lander-10266, and a custom display case.