Indeed Maxi Cosi do 2 different bases one isofix one not but if push came to shove you can still fit the seat the old fashioned way without a base since the seat will have all the routings for the belt still in situ.
I would urge parents to always get an ISOFIX seat if your car has the function it is the safest most secure and most foolproof method available. It was astonishing the amount of traditional style seats i saw fitted poorly in my old job.