You can use a screen reader to quickly get a sense of what’s on a page by jumping from heading to heading. The headings form a table of contents for the page.

For headings to structure page content they should be nested by their rank. H1 always comes first, followed by H2, H3, etc. You can move up, say H4 to H2, out of order. Descending headings need to maintain the heading hierarchy.

heading levels - h1 > h2 > h3

Make sure every page has a title – an H1. Text added to the “Add title” field becomes an H1.

the "Add title" field

You can also add an H1 in the body. Start a new block, choose headings, select H1.

H1 is selected in the heading block