How To Select Multiple Sections of Independent Text?

I am encountering a problem.

How can I select multiple sections of text by mouse “painting?”

In traditional Windows-based word processors, one could select a sentence, then hold CTRL+SHIFT, followed by selecting more text, and each isolated section would be selected.

This allows me to change the size of the font for multiple headers in the same document, for example, without having to manually select and change each one individually, one at a time. This way, I could select all of the headers, via mouse “painting,” and then I could change their size, etc.

OR, is there a more effective alternative to this?