Rubik's cube: rotate 2 opposite corners

This algorithm can be adapted to do what you need.

F D' F' D F D' F' U' F D F' D' F D F' U

To deal with non adjacent corners where one corner is on the right hand side of F (corners in a diagonal), rotate U twice instead of once in the algorithm, i.e.

F D' F' D F D' F' U2 F D F' D' F D F' U2`

If both corners are far opposites (do not share any faces), make sure one corner is on the right hand side of F (as before), rotate L2 and then apply the original algorithm, and rotate L2 to finish.

Twist two diagonally opposite corners. One is twisted clockwise while the other anti-clockwise.

U L U' R2 U L' U' R2 D L2 D' R2 D L2 D' R2

This rotates front right clockwise and back left counterclockwise:

(R'D2R B'U2B)X2

You can rotate the cube to avoid having to turn the back side but this orientation has the handy "hardy har, bub" mnemonic.

Consider algorithm 25 on this page: https://solvethecube.com/algorithms

It is this: F' (r U R' U') (r' F R)