Yes, you can. To watch the Sky Sports channels in full HD, you'll need to upgrade to NOW Boost. It costs just 6 a month, and for that you get: All Sky Sports channels in 1080p with Dolby Digital 5.1 surround sound.
Without the additional Boost Membership it will be 720p. With Boost you get 1080p on most devices, but more importantly you get 50fps instead of 25fps on most devices which makes a big difference in my opinion when watching Sports.