I’ve seen a plugin somewhere that I thought offered to modify the built-in WordPress engine but I’m gonna tell you…
If you’re doing this to influence the search engines you’re probably wasting time. Search engines are going to crawl through a website looking for those ‘dark cubbies’ that house some of the real jewels to be discovered in those nooks and crannies. Let them do that via whatever URL they find.
Spend your time creating content and making your site welcoming to the humans who visit there.
Install Yoast SEO and let it natter at you when it sees something it doesn’t like. Yoast knows SEO well and can guide you with better long term results than most any short term trick you’re likely to come up with.
Spend a few dollars on some business cards and hand them out here and there. Hope that they get lost because business cards ‘scattered to the winds’ often get picked up by someone with a bit of curiosity who will sometimes find a visit to your site the highlight of their week. And they talk.
There are times when a prettier URL is needed… This site will help you easily create 301 redirects that work well.
https://www.rapidtables.com/web/tools/redirect-generator.html