Have a look around for a recipe that specifies that abv rather than try and amend a recipe for something different.
Essentially you need a higher gravity wort, and a yeast that will tolerate that strength of alcohol.
You could get the higher gravity wort by concentrating it down, but it would be easier to just the appropriate amount of grain or extract to get the gravity you need.
If youre using kits as the base people generally don't recommend brewing them too short as the bitterness will be pushed higher; the concentrate will have been hopped to say 23L but you'll be getting that much bitterness in a smaller brew.