I have a theme called MediPlus. There is a services section within the menu. Within the services I can create posts or categories. No matter what though, the base url / permalink is always https://example.com/services/post
I would like to change the permalink only for the services to something else. I tried several plugins and permalink settings, but couldn't manage to only change it for the services.
Any advice is very welcome.
If it's part of the theme, you'd have to create a template override. This should be done by creating a child theme.
If creating a child theme, and making the necessary modifications to the pre-established system isn't an option, then as you noted in your comment, you would have to look at moving them to a post category.
UPDATE
If going the route of implementing different permalink structures for individual categories (to avoid theme modifications), you could look at using a 3rd party plugin to accomplish this. I haven't tried any of these, myself, but from the looks of them, these ones should do the trick.