Sometimes there is a port for bleeding but usually you break the line nut to release the air.
As stated by OTR tech, the Master usually only need bleeding when replaced and that is first done on the bench before install or if run completely dry of fluid.
If you are doing bleeding yourself get a Vac Pump Kit for bleeding the brake and do it from the bottom making sure to keep the master filled.
AND Start from the furthest away cylinder and more closer.
Sorry if this wasn’t what you needed to hear.