How can I update my iOS to 13

Is your device compatible to update to the new version? See the article(s) below. 

iOS 16 compatible devices

IOS 15 and iPadOS 15 Compatible Devices.  *

iOS 14 and iPadOS 14 Compatible Devices.  *

iOS 13 and iPadOS are compatible with these devices - Apple Support.  *

You can not, as that device is not compatible with iOS 13 or higher.

You can only update as far as 12.5.6