Can I use different SSDs with different operating systems on a MacBook Pro? I have an early 2013 Retina MacBook Pro with only a Windows 10 partition. MacOS is not currently installed on the machine. The Windows 10 partition is encrypted with BitLocker and because of the partitions layout, I believe MacOS cannot currently be installed alongside Windows.

Can I temporarily swap the original SSD for a new empty compatible SATA III and perform a clean install of MacOS on the new SDD? I would like to see if any EFI and SMC updates are available for the MacBook.

When I'm done with MacOS, I would like to put the original SDD back in and continue where I left off Windows 10.
The boot volume does not need to be internal for OS X. Use any USB drive, boot while holding cmd+R. You will boot the recovery partition (from the disk of existing or other online, so it might ask you for a network connection). 
Then just install on the external drive and boot from that by holding alt/option during startup.