Allow fingerprint unlock but require password after a certain time limit Currently with a Samsung Galaxy S8, but I believe this is common to other devices, I can setup fingerprint unlock which requires a password when the device starts up or if I fail to scan my finger correctly a few times.
I would like to add another limitation: allow fingerprint unlock but require a password unlock every x minutes/hours or some other configurable time limit.
A somewhat silly scenario to illustrate the need: suppose I fall asleep on the train, I don't want anyone to be able to scan my finger and unlock my phone. I still want the comfort of unlocking the phone with my finger while knowing that after a while it will lock itself and require a password.
Is there a setting I'm missing or an app that can do that?
Following @beeshyams's answer, here are my current settings.
Samsung has its own ways of implementation so this may differ but stock implementation :

Fingerprint can unlock the phone after it goes to sleep ( Settings &radar; Display &rarr;  after xx minutes of inactivity) only if Power button is not used to lock and default lock screen is used

If you enable power button locking or any third party screen lock / launcher that can lock screen, you can't unlock with fingerprint. You require to enter PIN

That is a far more easier way of achieving what you want (though you can't configure the delay) going by the need in your example

If you really need a configurable interval, that may be possible but would surely need root