Native Headings All the Same

I recently noticed that there seems to be no ability to change the various headings (1, 2, or 3) even though you can select them when you are formatting a post. This has lead to some confusing layouts when all headings look the same. How can I go about making discrete variations?

If you go into 'Design > Fonts > Headings' there should be a slider that allows you to change the size of all your header fonts.

Unfortunately, that's not a path that is available to me. My only path to editing headings is 'Design>Site Styles>Main Content>Headings