New master and calipers

I have not done this myself, but I learned that you can gravity bleed discs.

Open valve on caliper and let the fluid flow from master cyl to caliper. Be sure to keep master cyl topped off.

Does not work on drums due to residual pressure valve.
Yep, did it on my tool trucks for 3 decades. The bleeder should be at the top, crack it loose, put a pan below to catch the overflow and let her go. Like Dana said, make sure the reservoir doesn't run out. I always closed the bleeder and pumped the brakes up and bled again. Do the passenger side first.