Devices for a mesh testing scenario

Before I am changing my complex network, I want to do learn and test how to seutp a mesh network.

As master I would like to use
Asus RT-AX53U Router

As client mesh points
2 DAP-X1860 EXO AX1800 Mesh Wi-Fi 6 Range Extender

Is this enough hardware for testing a mesh?

The RT-AX53U will be later replaced with a TUF-AX6000 and the RT-AX53U will become a client mesh point.

My problem is, that I have to test this without any internet connection. At least with no wired internet connection.

But I could connect the RT-AX53U to a wds-client (Archer C7) using an ethernet cable between Archer C7 and RT-AX53U, but the Archer C7 itself is not connected via ethernet to the internet.