Customize HTML code – but where to find it?

Hello,

I would like to customize a bit more than CSS in the agenda and stream view, but I simply cannot find any HTML code in the files, e.g. in /wp-content/plugins/all-in-one-event-calendar/app/view/calendar/view/agenda.php I would expect the HTML framework, but I find only PHP code.

Also in /wp-content/plugins/all-in-one-event-calendar/app/view/calendar/view/single.php I would expect the regular building of the single event posts, and it even says on top “Renders the html of the page and returns it.”, but even here I can’t find any HTML.

I am not a developer and to adapt I would need to know where the HTML is actually put together. Anyone who already tweaked the HTML output can tell me where to actually find it?

Thanks a lot
Sofian

https://ww.wp.xz.cn/plugins/all-in-one-event-calendar/