Editing all H2 Headings

I want to edit all H2s.

h2 {font-size: 2.3rem !important;} does not work. It will only work if I assign the block like this...

#block-897e667f1a0639ee03e5 h2 {font-size: 2.3rem !important;}

How can I apply to h2's site wide. I would be using this in various media queries for mobile sizes.

Thanks

If you share site link to page where you use h2, we can check easer (maybe you have another code with higher priority, affects on h2)

If you can't share site, you can use this code to Code Injection > Footer to set CSS inline

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.0/jquery.min.js"></script>
<script>
jQuery(document).ready(function($){
  $('h2').attr('style','font-size:2.3em!important;');
})
</script>