I made a farm with cows, sheep, & chicken. If I breed them the babies stay babies unless I am close to them. So I will breed them and go looking for resources for up to 4 hours of in game time and I return and they are all still babies.
this also happens with the crops growth. If I am not near them then they won’t regrow.
Only chunks that are inside the Simulation Distance range of the player will be have any activity happen. So if you move more than 4 chunks away (with default settings) the mobs will stop "aging".