It’ll be 2x8gb and 2x16gb.
I had that configuration for 48gb before i updated my MoBo, mainly due to not knowing if another 2x8gb would work, so i added 2x16gb just in case. That way, if there were timing issues, i’d just remove the 2x8gb sticks and “make do” with 32gb.
As it happened, it worked perfectly, so needn’t have worried.