<p>I want to build a mini CNC machine and need some lead screws. I was wondering I can simply 3D print some. There are a few 3D models out there but I want to know if printing it in PLA+ has enough strength for a small CNC. Is it possible?</p>

Is it possible? Yes. Is it advisable?
No
Lead screws need to be smooth and have little to no stretch and there can be a lot of tension on them. However, 3D prints are quite rough by the way they are made and super weak on tension forces - and not have a good compression withstanding either.
a 3D printed leadscrew is therefore
not adviseable
, especially since ready-made leadscrews and fitting nuts are cheap in the shape of nuts and threaded rods for the crudest setup.