Others, of course, will have their preferences.
Dropping 12-strings by a step (or more) is typical. You can tune to concert pitch, but watch out for any potential damage. For many years I kept my 12-strng acoustic at concert pitch strung with 9's or 10's. I bought it around 1981 in Germany as a second, the headstock had broken off in transit and had been repaired. Within 6 months of playing at standard pitch the basic repair broke apart. So I got it repaired properly and it has survived ever since.
When the going gets weird, the Weird turn Pro.