Think they are in the process of tearing down the WB one (christmas vacation, bewitched, partridge family, wandavision, etc) to make room for sound stages.
The universal one is unique if you know what to look for. It pops up in a lot of older TV shows. It is kind of neat to see it in twilight zone before they built some of it out.
There are quite a large number of vids on youtube where people go inside the buildings. Most end up being storage for stuff or setup areas for different productions.
It's on the tour when they aren't filming other movies there.
Amadeus filmed there too.