Turning on a light from IFTTT auto turn off after x mins unless triggered from swtich?

There are two ways.

You could have IFTTT turn on a virtual switch which can act as a timer instead of directly turning on your regular switch. See the how to article in the community – wiki for setting that up:

http://thingsthataresmart.wiki/index.php?title=How_to_create_a_virtual_timer_for_a_light

Alternatively, you can use web core, which is a very powerful community created rules engine and lets you do all kinds of things. However, set up is fairly complicated and it might be overkill for just a simple light timer.

There are lots of community members will be glad to help you with it if you do decide to use web core. Here’s the initial FAQ for that: