How to change h2 tag into h1 in specific element (final HTML generated by wordpress)

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Javascript

plugin

CSS3

HTML5

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I would like to change h1 tag of one of my elements in WordPress page. Wordpress creates shortcode finally:

You can check html on WordPress site look in chrome web developer:

https://hyva-design.pl/

I would like to change only this tag generated by I think Javascript, not all of h2 tags on site into h1.

Which file in wordpress I need to edit to change h2 into h1 in this specific element? (Hover box)

Page is built by Visual Composer, overwriting class by custom css is not working. I need knowledge which JS file is responsible for creating this element and then I need to change it to create h1 instead of h2.

BTW. Is there any way to change final html output of wordpress? (This look when I enter chrome developer tool, same as html file - I don't see it on FTP but maybe it is some way?)

What I have tried:

Changing in theme options (no settings, this is impossible to change hoverbox addon settings to automatically generate h1 in this element)

Overwriting by custom css and giving element special class doesn't working

I cannot find specific JS file which is responsible for generating final html output