A keyboard is required. Shortcuts work only with a physical or Bluetooth keyboard attached to the device. There is no in-app setting to enable them.
Compose and reply. c composes, r replies, a replies all, f forwards, Ctrl+Enter sends, Ctrl+S saves a draft, and Ctrl+W closes and saves.
Email actions are single keys or Ctrl. e archives, # deletes, s stars, m mutes, z undoes, and Ctrl+U refreshes the inbox.
Navigation. j and k move between conversations, Enter opens a conversation, and Ctrl and comma opens Settings.
Text editing uses Ctrl. Ctrl+X, Ctrl+C, Ctrl+V, and Ctrl+A handle cut, copy, paste, and select all. The full set is in the table above.