Even if you don't have much space, you can still build a layout for your model trains!
One of our customers, David Noal, sent us these pictures. He has built a small/micro three-rail O scale layout that is 74" x 40" in total size.
The attention to detail in this layout makes it look very realistic.
There are many websites and Facebook groups that you can turn to for inspiration for designing your layout of any size.