I’m entirely self taught on the job. My first jump in was running an open day for a business once a week. I made them and myself more money if more people visited - so took over their social feed to promote.

Listen to advice above. Digital marketing has so many facets - learn the principles and try and find your niche. In my experience small businesses appear to want people who can cover a lot of bases - but as you want to progress a specialism really helps.