Most lenses can be made to fit on most enlargers.
The mounting system for enlarging lenses is generally really simple - there are threads at the back of each lens, and they either screw into a threaded lens mount/board, or go through a hole in a lens mount/board, with a retaining ring (jam nut) threaded behind, to hold them to that lens mount/board.
Each style of enlarger has a different approach to the lens mount/board issue - a Saunders lens mount/board will generally be different then a Beseler lens mount/board, which will be different then an Omega lens mount/board, but it is relatively easy to specify and find which lens mount/board you need, if you specify what focal length lens it is to be used with, and what the thread size is for that lens.
The most common lens used with 35mm negatives is a 50mm lens. If you did a poll, most likely you would find that the majority of 50mm lenses have 39mm threads - which happens to be the most common thread size for other lenses too.
For many enlargers, a lens mount that permits mounting the lens close to the negative is needed for 50mm lenses. As I understand it, the Saunders/LPL enlargers use a lens mount that you just turn upside-down to change the distance between lens and negative. So you could use just a single mount to change between shorter (50mm) lenses and the longer lenses (75-90mm lenses) that one would use for larger negatives. It is, however, much more convenient to have a mount for each lens if you intend to switch back and forth.
If an enlarger comes with a lower quality 50mm lens with a 39mm thread mounted in a lens board, it is relatively easy to start working with it while you look for a higher quality lens to swap it with.