You are one smart d00d aren't you?
A quick google for "convert exFAT to NTFS" revealed this:
https://www.disk-partition.com/windows-10/convert-exfat-to-ntfs-windows-10-7201.html (look at option 4, the others are just reformat/restore) - I can't vouch for it personally, but there are probably more if you google further.
Yes, that's a Windows app, but it is reasonable to assume that, if you need an NTFS-formatted drive, you use Windows in some form.
@posguy99 may have come over as unnecessarily snarky, but they're quite right.
No responsible person will advise you to try anything like exFAT-to-NTFS conversion (even if it was possible) without backing up first, in which case, for a one-off job, you might as well just re-format the drive and restore from the backup. You'll need Paragon NTFS or similar, but without that MacOS only supports read-only access to NTFS drives.