I have a Note 8 and I connected to my S3 weird Samsung Flow. I really don't see a huge positive to this so far, other than my tablet time being barraged with my notifications from my phone. Is there anything else to this?
You can also text from your tablet and, while pointless on the Tab S3 (it's better for Samsung Windows Tablets with no FP Sensor), you can use your Note 8 to authenticate your session on your tablet. The usual data transfer options are there as well. Again, this is more useful for Windows PCs than Android-to-Android, but the texting part is nice.