H1 tags and title issue

I noticed an ongoing issue with the theme. When trying to add <h1> heading to the title, there is always an issue. Instead of making the title bigger or (just keeping it the big title font, it shrinks the title size). So weird. However, if you use <h1> in-page it’s fine. Is there a way to just add <h1> to the title so that it big and bold like it’s supposed to?