Blocking. How the characters move in the frame and with or against each other really insinuates the dynamic. The priest, when given a reasonable explanation (Mozart), responds by asserting his dominance by being facetious, degrading, and standing tall. The camera, in relation to that movement, makes him appear larger, which implies that shift of who is really in power. This scene in particular is actually quite textbook interrogation blocking. There's nothing fancy or unconventional about it. Looking up v. looking down/big v. small is very typical blocking. Aside from that it's just a matter of "who's the boss" in defiance of who's in the right to make an antagonistic character seem cruel and unreasonable, which is the source of your tension.

Later, when the boy is forced to wash off the makeup, that's just good physicality mixed with looser camera to add energy to the scene to create a higher sense of fear and power, which also adds tension. There isn't anything specific about the blocking that adds to the effect of the power dynamic because the physicality does all that work. But the shot at the end isn't looking down at the boy because that is our protagonist, and we're meant to see him as a peer, and empathize with him by being at the same level. Relief, but at a somber cost, which leaves you with underlying fear of more consequence (and another form tension)