Don’t know when this feature arrived about its new at some point in the last year , I’d tried this before and it didn’t work, now it does.
You can now say
Alexa turn on|off in
Example
Alexa turn off lights in 35 minutes.
The event is then queued as a timer which you can see in the app or hear via
Alexa list timers
This means you can delete the timer too.
You can also use it as a sleep timer for listening to radio
Alexa stop after 1 hour will stop the playing of radio or music.
Yep. That capability had been available in Routines since 2018, but they finally added it to basic voice control in September 2022. Not sure why it took so long. 
Not really the same capability in routines though.
You have to use the wait function in a routine. Which means that once invoked you can’t cancel the pending action.
Wait option is inferior in this respect.
Just had a quick test and it does work in routines
What do you mean work in routines . You mean as a “spoken command” within a routine?
Yep, that’s using the “new” “after” functionality using the typed command as you would speak it.
Prior to this being launched you needed to use “wait” step in a routine which effectively made it a long running non cancellable routine.
I think there’s also a limitation on routines that you can only have one “spoken” command per Alexa routine
There is a limit of one ‘customised spoken’ instruction and it must be the last in the routine. So both this and ‘wait’ have their function.
