I see several H1s when I view your site. I recommend asking at https://projectdmc.org/support/theme/oceanwp#new-post so the plugin’s / theme’s developers and support community can help you with this.
I was under the impression that when I added a title it would automatically add the H1 tags – apparently this isnt the case. (Seems daft to me but that may be just be me not understanding things)
Note that titles of posts may be used all over the place: eg on an archive page where multiple posts (with their titles) are listed, “latest posts” listing in the sidebar, etc. And in many of these listings, you don’t want multiple H1 tags scattered all over the place… so it would be a problem if the H1 markup was tied to the title text.
As such, WordPress itself returns the unformatted title text. It’s left to theme authors to enclose the text in the appropriate HTML markup depending on where they’re displaying the title in their theme.
Most themes, indeed, use the H1 tag on the single POST/PAGE page. But it seems your OceanWP theme uses H2 instead. I’ve tested this to be the case. This is purely a design choice by the theme’s author. And their solution to “fix” this involves creating a child theme and adding a bit of code to the child theme’s functions.php file. See: https://docs.oceanwp.org/article/453-alter-the-single-post-heading-tag
Since you’re using the Elementor page builder plugin, another option would be to create an Elementor POST template to render individual posts (where you’d use your desired H1 for the post title), instead of using your theme’s template.
Ultimately, this is a theme issue… and if you need further help with this, please post in the OceanWP theme’s own support forum so the theme’s authors and user community can assist you: https://projectdmc.org/support/theme/oceanwp
Good luck!
Thread continues at https://projectdmc.org/support/topic/no-h1-tags-2/