If it's already off then it might be a hardware issue and I will suggest you to visit Samsung service center in that case.
A. Clear Wipe Cache Partition.
Steps to perform.
1) Turn off the device.
(Connect with type C cable/type C earphone only for Android 11)
IF YOU HAVE ANOTHER MOBILE THEN CONNECT WITH CABLE WHETHER IT IS TYPE C TO TYPE C OR MICRO USB PORT take help of otg connector to connect other mobile.
2) Press and hold the Volume Up key and the power button.
3) When the Android logo displays, release all keys.
4) Press the Volume down key to navigate and select "Wipe cache partition".
5) Press Power key to select. When the wipe cache partition is complete, Select Reboot System.
6) Press the Power key to restart the device.
B. Check in safemode and observe is there same issue in safemode too
if not then problem may due to other downloaded apps
and if same issue in safemode then try to visit service centre
steps to turn safemode;
long press on power button>
long press on power off option>click on safemode >your mobile will restart and turn into safemode.
Keep in mind that in this mode only inbuilt system app will work
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