Formatting Seagate External HDD with exFAT and APFS partitions on Mac

Hi, all, I'm new to Mac, And I was advised that I can format a Seagate External HDD into two separate formats, exFAT and APFS. Does this really work? I need to back up an exFAT 5TB's HDD with 3.5 TB of Images and Videos into that split HDD. Hope this makes sense. Don't want to buy another HDD. Just want to know that this will work.Help!