Are emergency vehicles ever able to influence traffic stop lights?

Today I believe I saw a traffic stop light cycle to accommodate an oncoming ambulance.
Is that possible?
If not, why not? It seems like it would be easy enough for an emergency vehicle to send a signal to a traffic light enough ahead of time to ensure that the light was green when the EV arrived?

I’m going to verify any answers I get here, but I thought it would be interesting to others, so I open it for discussion.