This is normal text, currently set at 18px, Archia font.

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Morbi blandit cursus risus at ultrices mi tempus. Quam elementum pulvinar etiam non quam lacus suspendisse faucibus.

This is a quote block. It’s a blockquote element with the class “wp-block-quote” , containing a paragraph. The citation is outside the paragraph, in <cite></cite> tags.

This is the citation.

Id diam maecenas ultricies mi. Ut venenatis tellus in metus. Quam nulla porttitor massa id neque aliquam. Adipiscing commodo elit at imperdiet dui accumsan sit. Leo vel fringilla est ullamcorper eget. Scelerisque purus semper eget duis at tellus at. Ultricies leo integer malesuada nunc vel. Ac feugiat sed lectus vestibulum mattis. Viverra tellus in hac habitasse platea dictumst vestibulum rhoncus. Cursus risus at ultrices mi tempus. Mattis aliquam faucibus purus in massa tempor nec.

This is a pull quote. Quam elementum pulvinar etiam non quam lacus suspendisse faucibus interdum. Ridiculus mus mauris vitae ultricies leo.

This is the citation.

This is an h1.

This is an h2.

This is an h3.

This is an h4.

This is an h5.
And, finally, an h6.

As a new WordPress user, you should go to your dashboard to delete this page and create new pages for your content. Have fun!

This block is verse. Not at all sure what verse is supposed to be, tbh. According to wordpress itself "The options are the same as the paragraph block, but the verse block lets you add extra spaces between words and line-breaks within the block. The live site will display the spacing just as you typed it." It's contained within <pre class="wp-block-verse"></pre>. The pre tag defines pre-formatted text.

You might        
      write it like

This is the body font, set at 1.125rem.
This is 12 px.
This is 14 px.
This is 16 px, which is the closest to root.
This is 18px, which is pretty much 1.125 x 16px, or 1.125rem.