Software update taking long

• Make sure it's iOS version 14.1
• Connect iPhone to power adapter (not using Low Power Mode)
• Connect to the Internet via Wi-Fi (not to a Personal Hotspot)
• iPhone has 4-5 GB free space

Also see here => Update your iPhone, iPad, or iPod touch - Apple Support

Make sure that your iPhone is setup to meet the following requirements before you attempt to update the iOS version-

• Your iPhone must have a fast Wi-Fi connection; you cannot update over cellular data or a cellular hotspot
• The iPhone can not be in Low Power mode
• The battery state of charge must be above 50%
• Your iPhone must have at least 3 GB or more free storage space
• Your iPhone cannot be connected through VPN
• If you are not planning for it to update automatically you should turn this option off, as it will only update when the phone is plugged in, connected to Wi-Fi and locked
• You should leave the phone plugged in until it finishes updating, both to assure that it remains above 50% and to keep Wi-Fi enabled (Wi-Fi turns off when the phone sleeps if not connected to power).

Axel F.