HTML and CSS are the basics. Yes, very important.
I do have to say if you’re gunning for remote work, you’re going to have lots of more experienced competition. And companies that are hiring trying to be safe tend to give remote work to more experienced people who have a track record, that they have confidence can finish the job (since there is no one to oversee them day to day).
I suggest learn HTML/CSS (+ a little graphics, and how to create sites from a graphics mockup), learn some WordPress too, how to make sites using WP, maintain WP pages, or use themes to make WP sites for clients — then hit up the local small businesses in your area/town/city, including non-profits, churches, clubs, orgs.
Get as much experience as you can making sites for them. You’ll gain valuable work experience, make some money, and learn how to deal with clients, expectations, problems, billing … then after you have experience and feel confident/comfortable working on what typical clients ask from you, then look for remote work. (1) You’d have a portfolio of real-world projects/clients to show future clients, (2) You’d have more experience and landing a remote work will be more likely, since you’ve proven you can do the job