How do I set up a subscribe button on my blog?

This plug in works nicely.
https://www.ads-software.com/extend/plugins/share-and-follow/

That plugin doesn’t email, though, which is what most people mean when they say ‘subscribe’.

https://www.ads-software.com/extend/plugins/subscribe2/

I use feedburner from Google and once set up there is an option to publicize on your site. It allows you to use the normal rss button or any of a dozen others. that you can put into a widget somewhere on your page.

On my site https://jeff-foliage.com/ if you go to the bottom right you will see the subscribe button. I hope this is what you mean..