ONTAP versions come bundled with particular Platform updates (SP/BMC and BIOS), Shelf updates (IOM firmware), and Disk updates (firmware.) You can see which versions are included in specific ONTAP releases in ActiveIQ. For example, here is the table for ONTAP 9.3: https://aiq.netapp.com/system-firmware/major/9.3
Outside of ONTAP upgrades, you can manually download and update the Disk Qualification Pack which contains info on recommended disk firmware versions. For older versions of ONTAP such as 9.3, see https://mysupport.netapp.com/site/info/disk-qual#ontap9