there is a way to leave the great plateau with a very precise btb but the paraglider check picks it up before you reach hyrule castle or any further than the lake hylia region.

In my opinion skipping the plateau or glider get is pointless as Dark Beast fight teleports you to Hyrule field, so even if we managed to get to sanctum without the glider it would bring us back to SOR when it realized we didn't have it. Also plat is fun as heck :p