I got also an answer from Bubble support and they suggested these options:
Use a custom HTML element and put the text in the custom HTML element with the proper styling
Use a text element with the custom ID attribute and then use JavaScript that finds the element and styles it or a CSS file that finds the element by ID and styles it
There are separate paragraph input boxes for the article’s paragraphs. When I publish the article, I can modify the space between sections by printing those paragraphs under each other with the space I want to.
There must be a better design for this (maybe a repeating group for text input), but my brains did not work out at the moment.
If you have any ideas on making this work better, I would be happy to hear your advice!