Do you mean in the Content block editor toolbar? It requires some knowledge of CSS. You create a file called "typography.css" and place it in the root of your theme directory (it can't be in a subdirectory like "css" or anything like that). In that typography.css file you can add classes, and those classes will appear in the "styles" dropdown menu in the editor toolbar. But it is very finicky and there are some gotchas involved, most importantly that it will only recognize single class selectors. For example, ".big-red-heading" will work, but "h1.big-red-heading" or "#big-red-heading" or "#wrapper .big-red-heading" will not.
Also, it doesn't always refresh itself to show the new styles, so you will need to clear the site cache and your browser cache, and maybe log out and log back in, and maybe quit and restart your browser.

If you're not familiar with CSS or none of the above makes any sense to you, then I think the only solution is to find a theme in the marketplace that has built-in styles to suit your liking.

Hi im sharing the info about Text CSS.
•CSS stands for Cascading Style Sheets
•Styles define how to display HTML elements
•Styles were added to HTML 4.0 to solve a problem
•External Style Sheets can save a lot of work
•External Style Sheets are stored in CSS files

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