Pick space efficient moves
You do not need racks. Goblet and Bulgarian split squats, dumbbell RDLs, floor and incline presses, one arm rows, and push up variations cover every major muscle in a few square meters.
Build a full body plan around adjustable dumbbells and bodyweight; use unilateral moves and high reps to make light loads count.
A small apartment gym with dumbbells or bands can grow real muscle if you use unilateral moves and higher reps to make light loads hard. Run full body sessions built on goblet squats, Romanian deadlifts, dumbbell presses, rows, split squats, and push ups, taking sets close to failure. When weight runs out, add reps, slow the tempo, and shorten rest to keep the stimulus high.
You do not need racks. Goblet and Bulgarian split squats, dumbbell RDLs, floor and incline presses, one arm rows, and push up variations cover every major muscle in a few square meters.
When you cannot load heavier, work single limb versions, slow the lowering to 3 seconds, and take sets to within a rep or two of failure. A pair of adjustable dumbbells taken close to failure builds plenty of muscle.
Track reps and add them week to week, then shorten rest and add tempo before you finally add load. Bands can add tension at the top of presses and pulls where dumbbells feel light.
Build a full body plan around adjustable dumbbells and bodyweight; use unilateral moves and high reps to make light loads count.