Lvm could be the way to go. Start with the minimum amount of partitions (i.e. / and /boot and swap as lv, maybe efi as a real partition). Add additional lv later if/ when you need them. You can always re-size a partition and the wrapping lv when you want to re- distribute storage-space.

I never needed more than these partitions. But that is just my use case.

Edit: oh. Missed the Multi boot point. Forget what I wrote. :)