What is your end goal? How old are you? How much time do you have? That will help to align what to study. Maybe something like Cape Air would be a better fit to start? If so, you’d want to be sharp on round dials. Maybe C208 for a FedEx feeder? Maybe SIC in a 135 to bridge the gap. Taking a year and working 135 before 121 might help bring you up to speed. Or, if you think you have the skills, fly some sim time and study 121 stuff.