You should think in gear ratios.
You can work out what is equivalent, assuming that the wheel size doesn’t change, by dividing the number of teeth on the front by the number on the back.
30:25 = 1.2
For doubles you have the option of Compact, Semi compact and standard.
The smallest ring on the front is going to be 34,36 or 39 in each case.
For a 34t front you need a 28 on the back, a 30 or 32 would be a bit easier than now.
For 36 you’d need a 30t
For 39 you’d want a 32 but that would be a little harder.
If you are getting a new bike with 11speed then I’d suggest 52/36 p front and an 11:28 out back for most things.