How to narrow down my sites

Most formatting changes can be done by adding what’s called CSS rules, but tt depends on the theme that you are using. If you post a link to your site, it will be easier to offer suggestions.

i use Zerif Lite

okay so only with CSS ?

isnt there a plugin for it or something?

Yes, basically, only CSS. There is no plugin that I know of that will make the content width of a site narrow, because, as I said, each site is constructed differently and have different classes & IDs for their elements. You will have to either create a child theme or use a Custom CSS plugin like Jetpack or Custom CSS Manager to add the CSS rules that you will need.

You can try posting your question in the Zerif Lite support forum and see if the theme developer has a suggestion, but in my opinion, you are better off just switching themes to one that has the layout that you want.

okay can you recommend any themes with narrower sites?

thanks for the effort by the way!