Repair the area, not the whole floor.
A defined section of LVP, LVT, or carpet tile can be opened, corrected, and closed back into the existing field. Transitions that have failed at a doorway or height change are handled the same way: the failed piece is addressed, not the rooms beyond it.
If the rest of the floor is no longer sound, a patch will not last. In that case, see Luxury Vinyl Plank & Tile or Carpet Tile Installation for replacement of the field.

