There are several versions of key blanks. As said, I recommend talking with your dealer.
Here are 2 listed for a 2021 SxS1000M3D. Fitment will very depending on your actual switch.
KEY, BLANK(TYPE1) (KEYNO. AXX / BXX)
35121-HL1-A01
or
KEY, BLANK(TYPE2) (KEYNO. CXX / DXX)
35122-HL1-A01