my iphone 11 strucking/switching off when entering 4 number pass code

Welcome acyutha,

To make sure we're on the same page, when you attempt to enter in your passcode, the iPhone restarts or turns off?

If so, this could be related to a few things. For example, did you have issues with your iPhone storage being full prior to this happening? Does it ever reboot to the Apple logo only or a spinning gear?

If needed, see the following, which may be related to your concern:

If you forgot your iPhone passcode - Apple Support (For earlier iOS versions)

If using iOS 15.2 or later: How to remove your iPhone, iPad, or iPod touch passcode without a computer - Apple Support

If possible, are you able to determine the iPhone storage (if it stays on long enough)? If so, see: How to check the storage on your iPhone, iPad, and iPod touch - Apple Support

Let us know if this helps out or not, take care.