One of the questions I’ve grown to dread in my years of working with SharePoint is “can we change the URL of my site?” Up until now, the answer was pretty much no, unless you wanted to go through major hassles to create a new site, copy over content, etc. However, Microsoft has finally rolled out a feature to allow you to truly rename a URL, *and* it handles automatic redirects if someone uses the old URL. There are some caveats that I’ll point out at the end of this tip, but here’s how it works…
In the SharePoint Admin console, I’ve got my site named DufSite (/sites/DufSite) which should have been Duff Site (/sites/DuffSite):

In the Properties pane for that site, there’s an entry for the URL, along with the Edit link to change it:

All I need to do is provide the new URL I want to use:

SharePoint makes sure that URL is available. Once I’m OK with the new name, I click Save:

The process then asks if I want to also change the name of the site. In this case, I click Yes:

I enter the new name of my site, and SharePoint once again confirms that site name is available. If I’m happy with the new name, I click Save:

I now have a site with a new URL and name:

As you might imagine, there are a number of effects that happen when you change the URL of a site. These things involve permissions, redirects to the new site, what happens to things in the recycle bin, what happens to Flows and PowerApps, and so on. Veronique Palmer has a very good write-up on this feature at https://veroniquepalmer.com/2019/10/18/how-to-change-a-sharepoint-online-site-url/. I strongly encourage you to read it before you start down the URL change road…