LG G2 — Pattern unlock after x minutes

I recently changed over from a Samsung Active S4 with Android 5.0.1 to a LG G4 with Android 5.1. With my old Samsung phone I could set the pattern lock to lock after 15 minutes idle. Even if I turned the screen on and off. After 15 minutes of inactivity the pattern lock would activate.

I'm having a hard time trying to do the same with my LG G4. I have "Power button instantly locks" set alongside "Smart Lock" settings (On-Body Detection) so that when I hit the power button I have to swipe or in most cases pattern unlock. If I leave "Power button instantly locks" off and hit the power button it turns on the phone without having to swipe and accidentally click on apps.

I just want to know if it is at all possible to just have the phone pattern unlock after x minutes idle and before this limit be able to hit power button and just swipe to unlock.