Publishing a page is not the finish line. SEO also means checking what actually happened, and changing the page based on what you learn. Two free tools help with that, and the whole thing runs as a loop, not a single step.
Google Search Console
Search Console is like a report card for how your site does inside Google Search itself: which pages made it into the index, which search words actually brought people to your site, your average position in results, and whether Google found any problems.
Google Analytics (GA4)
Search Console stops at the click. GA4 picks up from there: once someone actually lands on your page, GA4 shows which pages they look at next, and what they do.
Turning data into action
Looking at this data, you can ask simple questions: Did a page's position in search drop? Which pages get clicks but few visits? Which pages could use a better title, or more complete content? The answers tell you what to change next.
A repeating loop
Good SEO work is a loop, not a single step: make a change, wait for the data to update, check the result, then decide the next change — and go around again. This is why the small test site you are reading now exists: it is a safe place to run that loop.