Redirect for SEO?
 

Yoast Word Press SEO has a few items it says needs work. One is this

"The keyword / phrase does not appear in the URL for this page. If you decide to rename the URL be sure to check the old URL 301 redirects to the new one!"

site is lollipopx.com keyword phrase is niche to "erotic blowjobs"
So wondering should I bother or leave it.
Otherwise its suggesting I make it redirect to ]lollipopx.com/erotic-blowjobs[ to include the niche keyword phrase in the url.
How will this affect the site?

Why don't you ask that on developer's forum?

One of the most touchy items in SEO is changing your url structure, if I were you I would play around with titles on the pages, but not with urls, since you need to be very careful with the redirections, and updates.

There are some plugins for this, just do a search.