serious question.
What does an online trainer actually do? why not just get a trainer at the gym who can help you push that little bit extra.
The good ones will customise your training programming/periodisation around your life in terms of days you have free, what your recovery is like, what your goals are and more importantly how you respond to diet/exercise (for instance some people just don't do well with hitting the same weight for x amount of sets v.s. pyramidding down, aren't built well for certain movements, have better/worse recovery time than average) and try and optimise things for you to make progress, identify/fix your weak points etc. You won't follow a cookie-cutter beginner routine and everything is tailored for you. There is obviously the accountability element in terms of having someone to report your progress (or lack of) to.
Generally you have several kinds of online trainer:
1) those who work with mostly beginners for things like diet accountability/adherence/protocols e.g. Andy Morgan from RippedBody.JP or JC Deen, who are trying to teach you to walk for yourself when it comes to nutrition and being able to be in control of your body composition. Typically they keep training simple as most clients are fat untrained people looking diet get lean for the first time in their lives and stay that way.
2) Those who work with people who know what they're doing for physique 'sports' contest prep/off-season for getting to
extremely low body-fat and/or the psychological stuff that comes with that, as well as structuring their transition into an off season so clients don't not go off the rails, e.g. Team 3DMJ. Bodybuilding stuff basically.
3) Those who work with people who know what they're doing for powerlifting/strength sports like Greg Nuckols, The Strength Athlete etc, and there are a couple of people that offer weightlifting coaching online although they concede they'd rather you have a coach physically with you.
The latter two are similar to the kind of coaching an actual athlete would get at best, and at worst they're just rinsing people of their money. The examples I listed would be the former though.