My update is stucking on estimate time remaining

If any of the following are true, they may be the reason it is stuck on updating:

• You are running a beta of iOS 13 or iOS 14. You will need to remove the beta profile first.
• Your phone does not have enough free space? Typically it should have at least 5GBs available to update.
• You have either or both Low Power Mode or Personal Hotspot enabled?
• Your phone is not connected to power and it has less than 50% charge left?
• The phone is not connected via Wi-Fi to the Internet. It won't update on a cellular-only connection.

Ref: If your iPhone, iPad, or iPod touch won't update - Apple Support