I agree. Can you explaim better yours ideas on the matter?

Well, those cities are huge in battle but with the standard garrisons feels like they dont use all their potential. I had in mind an exclusive and better garrison (land and naval if they have port) to defend them. I was looking to make walls and doors also harder to destroy but i cannot do that changes just on those cities. Maybe increase the siege time needed to capture and some base income...

What i really want to do is make them a real challenge, so you need more than just an entire army to conquer them, if u finally take them u get an strategic point so it is worth it to siege them.

I just think that, in general, garrisons (especially for provincial capitals - walled settlements) need an overhaul to present more of a challenge, not just the legendary cities. I used to use a mod by Prime called Realistic Garrisons, but after Empire Divided and his lack of activity, it doesn't work on patches 18 - 20.

I think if you could make a mod similar to Prime's, for all campaigns, that would be pretty innovative and help solve your issue regarding provincial capitals not being challenging enough.