In a webmaster hangout on YouTube, Google’s John Mueller said that the order of the h-tags on your web pages does not matter. That means that an h3 tag can come before an h1 tag on a page.
“[The order] doesn’t really matter. We use the headings to understand the context of the content on the page a little bit better and for that, we don’t need like a strict order of the heading tags.
Sometimes you have multiple h1 [tags], sometimes […] the order is slightly different because of your template or something on your page and that’s perfectly fine.”
Should you use headline tags on your web pages?
Headline tags are one of many signals that Google uses to rank web pages. Although it isn’t strictly necessary to use these tags on your web pages, they often help to improve the position of a page for a particular keyword.
Check your web pages with the Top 10 Optimizer in SEOprofiler to find out if your web pages contain all elements that are needed for high rankings: