If you like playing with fire, you can grab the latest version of Samba from Slackware:
https://mirrors.slackware.com/slackware/slackware64-current/slackware64/n/samba-4.17.5-x86_64-1.txz.mirrorlist
Put that in your /boot/extra folder and it'll install Samba 4.17.5 over the version shipped by default.
If you want to avoid a reboot, open a terminal and:
installpkg /boot/extra/samba-4.17.5-x86_64-1.txz
Then restart Samba:
samba restart