Once created the first time with what you type as a title, the slug can be changed independently. It’s like having 2 field: slug and title.
Now that this is said… I’d like to add an opinion.
Always add an independent Title to your collections. Don’t assume the NAME filed is the title For example “Blog title”. Even if most of the time you end up having the same NAME and POST TITLE.
You should never use the NAME field as your post TITLE. For many reasons:
the NAME field is limited because it’s used as the slug for the post
you can want a different slug than the title, you can want to change the slug but not the title
very difficult to handle accents and punctuation by using the NAME field only. If you title is “L’arrivée au port de Brest” then the slug will be as ugly as “/l-arrivee-au-port-de-brest” when you’ll probably want it to be “/arrivee-au-port-de-brest”
you can want a very long, slogan title, that is a real sentence with a developed idea in it (which is recommended), and a more effective, more compact slug.
NAME field is limited to 256 characters when an extra text field for Title would not.
Sometimes, Webflow itself pushes you to make this mistake (using the NAME field as a TITLE): when you create a CMS in your site, when creating the first collection Webflow propose some templates. Chose the Blog template and you’ll see that there is no Title field. Only the name field is supposed to work as a title for the CMS record.