There are lots of materials on how to procedurally generate levels for a videogame, but they mostly focus on obtaining the layout of the level and exist in a vacuum where having generated said layout means you have reached the end goal. For 3D games, however, it is rarely ideal to just have empty rooms connected by similarly empty corridors - you want to have some kinds of props and decorations all over the level to make it more appealing.
What approaches are there to reasonably decorate a procedurally generated level?
Before you can even begin to place props in a room you need to know what type of room it is, because what props are acceptable candidates for placement depends on the room(bookcases are welcome in libraries, but not in bathrooms). The problem with any generic level generation algorithm is that you end up with a bunch of nondescript rooms, so you will need to have an algorithm that somehow identifies and assigns room types by their properties.
The problem grows more complex when you realize that some props have more placement constraints - chandeliers can't be placed randomly as we expect them to be placed according to some spatial patterns.