Setting Word Limit for Manual Excerpt before "Read More"

Greetings,

New to GeneratePress, so far I am impressed with its features and speed. Eager to learn more about it. But for today, a question:

We use the manual Excerpt box in our posts to write custom excerpts for use on the blog that we repurpose for social media and search. Thanks to existing documentation, I figured out how to add a "Read More" button at the bottom of the excerpt display on the homepage and category page. But efforts to set a word limit on the display of the excerpt then cutting to the "Read More" so far have failed. I'd like to be able to have the first 25-30 words (or relative character count) to show, then offer the "Read More" button. Is there a setting in GeneratePress that does this? I've seen how to display the first few words of the actual post show then cut to "Read More", but have yet to figure out how to do the same with a manual excerpt. So I was curious if a solution already exists.

Thanks in advance. Learning a lot - GeneratePress is a big jump forward from our old theme.