Here's what I found on the manufacturer's website (https://support.apple.com/fr-ch...)

Memory characteristics
This model of iMac has SDRAM (Synchronous Dynamic Random-Access Memory) memory slots at the back of the computer, near the air vents, with these memory specifications:

Number of memory slots 4
Base memory 8 GB (2 x 4 GB DIMM modules)
Maximum memory 64 GB (4 x 16 GB DIMM modules)
Use SO-DIMM modules that meet all of the following criteria:

PC4-2400 (19200)
No buffer memory
No parity
260-pin
DDR4 2400 MHz SDRAM modules

In my opinion, this should be good because it's the SO-DIMM format, but nothing is guaranteed with Apple. If I were you, I'd contact them to be sure.

Have a nice day!