Years ago I worked for an international wire service that had portable photo transmitters that allowed us to send out photos from any place that had electricity and a phone line. I set up many a darkroom in tiny spaces in motel rooms, farmhouses and whatever. My notion is to start simple and go from there. I've personally used a shallow clothes closet for a darkroom and had to bend over to use the enlarger.
I recently bought an Omega B-22 enlarger which will take 35mm and 120 negatives but is pretty small in size although it is an extended model so its tall. I have tall ceilings.. I also bought a tiny Vivitar enlaarger. I don't have much space. I can put my soon-to-be-constructed darkroom in the big bathroom or the small one or put the film "soup" in the small bedroom and make photo prints in the larger one. I have not had a home darkroom sine before 1980 and it it gonna be fun.
The basic space you need is the table to hold the enlarger and three processing trays. If you have a separate wet area and it is dark, you just need the darkroom to hold the enlarger. It can be 4' x 5'?
For people with very limited space, a kitchen, laundry, bath or mud room is a wonderful place to house the processing equipment, be BW processing trays or a Jobo for color processing. You can put them away in closet when you do not use them.
A photo amateur
Sinar P2/F2/Nikon F5/F100/Bronica ETRSi/GS/Saunders 4550XLG/Jobo CPP2/CPE+/ColorStar 3000
My 'dark area' is in a room about 6' x 12'. However, the actual space I have for printing is just enough worktop space for the enlarger and three trays as the room is used for other things as well. The running water is in the bathroom which is the next room along.
I don't really know, can only guess. I left there in 1987. Probably 4 feet at the most. (Look at the picture) It was essentially a 10-12 ft. kitchen counter with a single bowl kitchen sink right in the middle. As can be seen in the picture, the enlarger (a medium format Phillips) hangs off the edge of the counter. I had more space not seen in the picture for storage, but it did not contribute to "darkroom" operations.