Which chess GUIs support the chess variants Atomic and King of the Hill? I want to play against Stockfish offline because I'm going on a trip. I downloaded the compiled exe from GitHub since my laptop will have limited Internet connection. After loading it into the Arena GUI I noticed it only supports Chess960. Which GUIs support the chess variants Atomic and King of the Hill?
There are three chess variant GUIs supporting both atomic and king of the hill that I am aware of:

PyChess
WinBoard/XBoard
Cutechess

The latter is well suited for automated engine matches and human vs. engine games, but less for game analysis. All three should work fine with the multi-variant Stockfish you downloaded.