This could be a tire issue or drive train vibration. Both would require a hands on inspection to fully diagnose.
If you don't work on your own car then use this link to find a good shop near you.
https://repairpal.com/repair-shops
Alex
RepairPal Certified shops can diagnose and repair your 2016 Subaru Legacy. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.