Can I use target disk mode from a Thunderbolt 3 mac to a Thunderbolt 2 for data recovery?
Yes, that should work.  I recall that working for me with a similar situation in the past.
Here's a couple links that might help.
https://eshop.macsales.com/blog/41010-mac-os-101-how-to-boot-and-use-a-mac-in-target-disk-mode/
https://support.apple.com/guide/mac-help/transfer-files-mac-computers-target-disk-mode-mchlp1443/11.0/mac/11.0