[mattbrewsbytes]

Find what interests you in web app development. You mention Fullstack but that really is a recruiter term.

Slowly building a set of problems you have solved is experience. As you encounter similar/same problems, iterating on those solutions makes you a better engineer. Solving those problems with increasing levels of traffic introduces/uncovers new problems to solve across the stack.

Learn from others, co-workers or other companies that publish things about the problems they have solved. Some of the BigTech companies generate frameworks or have services that solve BigTech problems they have encountered. There are solutions there that could be useful. There also are problems + solutions there that no other company is going to run into but people like to emulate so they will use those solutions like a square peg in a round hole.