Not new planets but new environments.
Habitable planets are very rare.
We need to build environments. Hollowed spheres, yes- even Dyson spheres, ringworlds, tunnel cities, whatever.
Look up 16 Psyche. 120 miles diameter of 90% pure iron/nickel, about 3 earth orbits out from the sun.
I think people will be turning it into all sorts of structures in the next 100, 500, or 2000 years.