Discount Coupon code entry

There is a coupon on my site which will be auto applied to all the users, if a specific condition is met.

Additionally, I want customers to enter the coupon code of another coupon manually to get additional discount related to the 2nd coupon.

I do not want to auto apply the coupon when a specific condition is met or via the URL.

So the first coupon should be auto applied and the second coupon should be via manually entering the coupon code.

How to do this ? I do not find any option to set manual coupon code entry.