Suggestions

It's in the title. A set of config options that allow you to change the difficulty rules to be affected when entering a new dimension.

Solution

Set the dimension's ID, and then set the number that the difficulty will be. Lower valued dimensions will be ignored so something like entering the Nether after entering the End won't set the difficulty lower.

Difficulty could additionally be added to the difficulty scale and perhaps you could even change the difficulty cap and range the difficulty can reach? Just spitballing.