(I had to take a look at the keymap to verify, as I have been using a custom keymap for years.)
Yes, to switch to the second layer, you press and hold one of the FN keys and to switch to the third layer, you press the shift key in addition to that.
They do have a VIA-enabled firmware, in which you can change which keys are used for that in a graphical interface and, if you familiarize yourself with QMK and how to build it yourself (not as hard, as it may sound), you can have a keymap with as many layers as will fit in the keyboards memory and can have all kinds of useful functions.
My keymap for the Momoka has five layers, a key that will activate one layer when tapped and another when held, Home Row Mods (The keys on the home row produce letters when tapped and Shift, Ctrl, Alt and Win/Super when held), etc., etc.