I don’t think of DOM manipulation as an Algorithms and Data Structures issue. Algorithms and Data Structures are computational problems that span all programming languages. But DOM manipulation is pretty much just a JS thing. You might use some of the ideas from A&DS in DOM manipulation - like inserting something in a list or working with trees - but it is really a separate topic, I think.
A lot of modern development doesn’t use direct DOM manipulation, for example, in React, Angular, Vue, etc. It is probably still a good idea to learn the basics, at least. I seem to remember FCC going over the very basics, but I could be wrong. Maybe I’m thinking about the jQuery section, which does some DOM manipulation. If not there are plenty of sites that can help you get the handle on it. But unless you have a very specific reason, I would not worry about getting too deep into it.