The S10 lineup, which Samsung will assuredly unveil this month, will be among the first phones to offer WiFi 6. They'll likely use Qualcomm's WiFi 6-ready Snapdragon 855 chip, which you'll probably see in other flagship Android phones this year. If you don't have a WiFi 6 router, and not many of us do as yet, the S10s should at the very least provide a degree of future proofing for when you do upgrade your home internet hardware.
WiFi 6 should provide sturdier, faster internet (particularly if you have a ton of connected devices in your home), while having less of a strain on your gizmos' batteries. Your devices will need to support it to get the most out of a WiFi 6 router, though.