Autopilot is there to reduce pilot workload. There’s nothing in the regulation that says you can or cannot use it (at least Part 91 which I’m flying under). The PIC is responsible, whether AP is engaged or not. Checkrides are obviously different, the examiner can tell you to use it or not to use it, etc.
Typically, under VFR, the autopilot would be used for longer cross-country flights or whenever you feel task saturated and you just need a minute to do other things like planning a divert, getting frequencies, ATIS etc. It also helps in busy environments but you should really be proficient in using it and never depend on it. It’s a tool that can help but nothing you should ever rely on for safety.