Yes, most showers can be upgraded to rain showers, but installation requirements will depend on your existing plumbing. A wall-mounted rain shower that aligns with the current water outlet is usually the simplest and most affordable option.
However, standard rail showers with a separate water inlet are often positioned to one side. Changing to a centred rain shower or a different mounting style may require the pipework to be relocated behind the wall, along with possible tile and waterproofing repairs.