Pitch Count Precedence for young pitchers/pitchers off injury.

I am interested in understanding how doctors, teams, etc. decide whether 1. A player will be put on a pitch / innings count when coming off of injury or just being a young pitcher (particularly interested in Garret Crochet) and 2. The details on the inning count and whether or not these can be violations of contracts in any ways (either a player declining to pitch further or a team forcing A player to pitch, preferably the latter)

I am assuming they are team doctor recommended, but given the unique situation of Matt Harvey who ignored that doctor recommendation and Garret Crochet seeking a contract if he does get traded to ignore that inning count. Any information is helpful as I cannot find much online.