How would i do this?

I am planning on using the 3v3 pin to spoof a momentary on push button switch but I only have one 3v3 and there is also a separate off button. So how am i supposed to turn it off
this is on a coffee machine.

This is how I “spoofed” a momentary push button for my garage door opener. Set up a transistor-relay circuit and connect one of the pins to the transistor base as digital out, and connect the relay contacts to your switch. Leave the relay normally open when you boot up, then at some command, close it for a second and then open it. In your case you would want two relays, one for power on, and one to start brewing. Here is the post about building my door opener…

There are a number of prebuilt relay circuits out there, if you don’t to build your own, even though it is a very simple circuit. I know there are several for the arduino that should work. There might be a more elegant way to do this, but I haven’t seen it so far.