There is no simple career path. In fact, it's a jungle.
There are four well beaten paths:

Journalism - lots of ex-journalists move into freelance copywriting. They have the skills, understand the pressure to meet word-counts and have learned to deliver to tight deadlines. They tend to start off providing Press Releases and ghosted articles.

Ex Ad agency - advertising agencies do take on trainee copywriters. First job (just like the journalists) is making the coffee. They may have been taken on as trainees in some other discipline, but with opportunistic career juggling, end up writing ads, jingles and sales brochure copy. Breaking out as as a freelancer, they tend to start writing sales letters, direct mail and adverts.

Ex marketing managers - lots of people percolate up into marketing positions in large organisations, often having started in sales. They usually start freelancing by writing sales brochures, web copy and, possibly, corporate video scripts.

Ex 'nothing-to-do-with-any-of-the-above-but-with-the-balls-to-have-a-go'.- Been around a bit, good with words and resiliant. Most hopefuls reading this article probably come under this heading. So that's the area I am going to address.