Set variable with Google

Is it possible to set a variable in Google Home? For example Hey Google, set ‘Tijd weg’ to x.

I want to use it for turning of the heater or airco when I am away for more then x minutes. I’ve set up this flow that turns off the central heating and airco’s when there is nobody at home for 60 minutes (my default). But sometimes I know that I will be back in 90 minutes, so I temporary want to change the timer to 90.