Hi Davide, if you mean 'how to make hand menu visible in the Unity editor', you can change MRTK's input simulation 's default hand pose to 'flat' then use CTRL key to rotate simulated hand.
About the hand menu:
https://docs.microsoft.com/en-us/windows/mixed-reality/mrtk-unity/features/ux-building-blocks/hand-menu?view=mrtkunity-2021-05