Sounds like you need a custom control, as I do not recall anything OOTB in the product for this.
I've attached a sample I took from W3Schools which I've also modified to add a button, and and input field where you can set your timer accordingly.
It's obviously just a starting point, as there is no error handling or other safety nets to reset the timer if you try to add more than one before the first one ends, etc.
But hopefully it will give you an idea of what can be done and where you can take it. (You can also look for other date or timer libraries on the web which could make this even more trivial. But I wanted to demonstrate an example using pure JS)