As far as I'm aware the BPMN standard does allow this, and you can find various resources on the net which show Receive tasks with timer boundary events.
Two Step Escalation: Solution 2 has a timer boundary event
https://camunda.org/bpmn/examples/
It's such a natural expression of how to handle waiting for a message which never arrives or fails to arrive within a timeframe.
Create a Receive Task, the only available boundary event is Error.