i3 only has two modes by default. You can create whatever modes in i3 you like.

    set $mediamenu "media:  [spc] play/pause [p] prev [n] next"

    mode $mediamenu {
        bindsym space exec "playerctl play-pause; i3-msg mode default"
        bindsym p exec "playerctl previous"
        bindsym n exec "playerctl next"
        bindsym Escape mode "default"
        bindsym $mod+m mode "default"
    }

    bindsym $mod+m mode $mediamenu

Now $mod+m will enter 'media' mode, with its own set of keybindings.

XMonad can presumably be modal if you configure it as such. I've got some modal behaviour out of ratpoison by swapping out my top level key maps.