Changing the font size of texts in the editor

Hello friends and dear support When I write a text in the editor, the size of the text is 13 pixels and we really don’t see anything Can you send me the css code so that the text I write in the editor is always 20 pixels in size? (I know it is possible to increase the size of the text through the editor itself, but this is done manually and if I want to do this for every text, it is really annoying)