Ok. Got it. The URL type field hides the Max Length field on the Dictionary form by default due to a UI Policy. But there isn't really a good reason for that -
Browsers support URL length up to 2,083 characters
The URL field is just a String field in terms of data type. Modifying String fields to larger Max Length is a simple process of changing the value of the Max Length field.
https://docs.servicenow.com/bundle/istanbul-servicenow-platform/page/administer/reference-pages/task...
So all you need to do is get around the UI Policy. To do this do the following:
1. Open the Dictionary record for the URL field
2. Change the Type to "String" (don't save yet)
3. The Max Length field will appear.
4. Change the Max Length to 2,083 (or whatever you want)
5. Change the Type back to URL
6. Now you can save your changes.
