Yellow Belt is a solid starting point, but it's mainly meant to build awareness of Six Sigma basics and terminology. If you're aiming for bigger process improvement roles or want to lead projects instead of just supporting them, you'll likely need to move up to Green Belt or beyond at some point.
That said, Yellow Belt still holds value on its own. It shows employers you understand quality fundamentals and can contribute to team projects, which matters a lot for entry-level or support roles. Whether you need more depends on your career goals and the kind of responsibilities you want down the line.
If you're unsure which path fits you best, CertBoosters has a helpful breakdown worth checking out before deciding your next step: www.certboosters.com/iassc/path/lean-six-sigma-yellow-belt