Is it really random? There are over 2 billion possibilities for non-hardened addresses. How many do you plan to look through?

You can generate 20 new change addresses using the code below on the console tab (view > show console if you can't see it) but it'll only create them sequentially starting from the index of the last generated address not randomly in the chain:



BTW default gap limit (last used+) is 6 for change addresses. AFAIK you can't change the gap limit for change addresses only generate new addresses manually.