Can I update my iPhone 6 to iOS 13.5.7?

An iPhone6 is incapable of update beyond iOS 12.5.7.

Whether or not you are able to update any iPhone to a newer version of iOS will be dictated by the iPhone model - and the currently installed version of iOS. You can find this information here:

Settings > General > About

Not sure which iPad you have? Identify your iPhone model - Apple Support

Here is a list of the highest version of iOS supported by recent models of iPhone (for simplicity - “generations” are shortened to a number), older devices being restricted in their ability to be updated:

iOS16.6

iPhone 14 (all models)

iPhone 13 (all models)

iPhone 12 (all models)

iPhone 11 (all models)

iPhone X, XR, XS

iPhone 8 (all models)

iPhone SE2/SE3

iOS 15.7.8

iPhone 7 (all models)

iPhone 6S (all models)

iPhone SE1

iOS 12.5.7

iPhone 6

iPhone 5S

iOS 10.3.4/3

iPhone 5/5C

Your iPhone 6 can not be updated further.