Do you really mean “mode”, as in thermostatMode which can be one of heat, cool, auto, off?
Or do you mean program/climate/custom comfort setting, e.g Away, Home, Sleep?
I ask because the Mode/Routine/Switches/Program Helper can’t change the thermostat Mode, but it can change the program. And if the requested program is different than the currently scheduled one, the only way to set the requested program is to set it as a hold - just as would be if you were to change on the thermostat itself (or using the Ecobee mobile or web apps).