When renovating a bathroom are the mechanical parts included?

If you mean the ventilation, plumbing, and electrical parts. The answer is “Yes,” because this is the purpose of a renovation, to address all issues with the existing fixtures, and all cosmetic properties of the space. This translates into replacing worn drains and bathtub overflows, new shut off valves for the toilet, replacing electrical outlets with upgraded GFCI’s along with light fixture and switch replacement, in addition to the ventilation fans.