Should I use an essay template for my senior English capstone, or will my professor consider it plagiarism?

Use the template as a scaffold, not as a finished product. A generic outline that tells you where to place your thesis, evidence, and analysis isn’t someone’s original work, so it won’t be flagged as plagiarism—as long as you fill every section with your own ideas and citations. The benefit is that a clear structure lets you see where each source belongs, which will tighten the flow you’re worried about. For instance, you could take the template’s “introduce source → explain relevance → connect to argument” block and plug in your own primary text, then write a sentence that links it back to your thesis; the resulting paragraph is entirely yours. Just avoid copying any phrasing that’s unique to the template’s author and make sure your bibliography matches the sources you actually use. This way you get a polished organization without risking academic‑integrity issues.