You can synch the dimmers to go on/off as described in the other topic.
I have been able to successfully create automations to match the on/off status of two devices by creating two automations. a) If either Switch 1 or Switch 2 is ON, then turn ON Switch 1 and Switch 2 and b) if either Switch 1 or Switch 2 is OFF, then turn OFF Switch 1 and Switch 2.
What dim level they come on at depends on the available settings in the driver for that particular device. For instance, using the GE/Jasco Motion-Dimmer driver from @philh30 exposes the Default Dim Level setting which determines the behavior when the dimmer is switched on from the button, the ST app, or a Routine that doesn’t explicitly set the dim level.