A default set of bindings for 2 players are available under "binds.godot" which can be copied into your project file under the input map section. Make sure to create at least 1 custom input first so the section appears. To create bindings for a second player, make the binding's number "jump_0" equal the player's ID, e.g. "jump_1" for Player 1. For analog sticks, make sure to turn down deadzone to ensure small movements are possible.
forward_0
left_0
right_0
back_0
Movement. Set to left analog/wasd
jump_0
Self explanatory. Set to A button, Spacebar
look_up_0
look_left_0
look_right_0
look_down_0
Look controls for gamepads. Set to right analog. Mouse is already handled
mouse_escape
Escapes and returns the mouse. Set to escape