Hey, Where Could I switch it to H1?
I am not sure we can tell you the exact place where this has to be changed, because it depends on the theme you are using. If this is from your home page you can check out the index.hbs (or home.hbs) and it’s probably rendered with a partial like post-card.hbs or similar.
It’s best if you reach out to the theme author and get the exact place where this can be changed.