Is there a way to add a linked button to an external website to post excerpts?

I am going to be making a few websites and would love to be able to use oceanwp, but I can’t figure out how to do what I want to do.

Let’s say I have a blog post, the excerpt of which will show on the homepage, which consists of most recent blogpost excerpts.

For SOME Of the excerpts which appear on the homepage, I want, instead of a read more button, a button that I could name what I want, and for that button SOMETIMES to link to an external site.

For example, if you go to https://tattoo-journal.com/ (not my site), see how on each grid it says read more? well imagine if, instead of read more, the button was called “go here to sign up,” and it linked to some other website.

I know how to use the read more tag- a workaround would be that I could put a button at the top of my post, add some text and then insert the read more tag, but I’d much rather be able to do this in excerpts so I could customize the text better.