Yes, you are going about this the wrong way.
What you don’t seem to appreciate is that the presentation / layout / display of your text is controlled by the css (Cascading Style Sheets) of your website.
When your browser loads a page, it is given a list of css files to load, so that when for instance it is given a h1 block, it can lookup everything it needs to place it on the page, it knows the font and size, color, surrounding margins and padding, effects such as underline or bold, also background, and so on. Just some of these properties will have been specified explicitly, many will have default values and also values inherited from enclosing aspects of the page.
It is the theme author who makes most of the design decisions about how their theme displays content, they do this with the css files in the theme. As a website developer you get to choose the theme, you also have the option of modifying, supplementing and extending any of the css choices, though you can just edit the files, the recommended way to do this is by using either a child theme or employing one of several custom css methods.
Rather than pursuing this abstract description here, it would serve you better if you were to put up links to pages you were creating, and described the changes you would like to see. The community here will then coach you with what code to use.