With my current CMS, I used URLs including the year, the month, and the title of the post. So basically like this: https://mywebsite.com/2020/01/my-post. With Grav, however, I can’t find a way to change it from https://mywebsite.com/my-post to the old format.
There are a couple of posts on this from before. Each one tackles the problem differently, so you’ll have to see which one suits your use-case best.
One deals with the problem by getting you to create folders for the relevant dates:
The other one shows how it is done with changes to the filename format (from what I can deduce):
If you just wanted to have the date in the URL and don’t need the folder structure, you could simply change the slug by clicking Options on the page (assuming you’re using the Admin plugin) and changing the Folder Name to something like 2020-03-15-here-is-my-dated-blog-post.