The online ones are all crap. The in-person ones are mostly crap. The key thing is the person's own experience. Every would-be trainer should have a trainer before becoming one. And they should have gone to a certain level in their own training. Then practice teaching others correct movement, etc.
Really PT should be an apprenticeship - straight out of school, apprentices have no clue, but they learn on the job. It's not structured that way so just do whatever course and then consider your first two years to be an unofficial apprenticeship.