How to update to previous versions

You cannot choose what version to upgrade on your phone - it’s either the newest or nothing.

However, for a limited time you can use iTunes to restore your phone to 12.4.1 - this wipes everything out so backup first. Search for “iOS 12.4.1 IPSW” and download the firmware file. Make sure the file link is from Apple regardless of the website you’ve visited to get the link. Hold SHIFT key while clicking restore iPhone, choose the 12.4.1 file you downloaded and it will install 12.4.1.

If you’ve waited this long to update to 12.4.1, you should wait a few more weeks for bugs in 13 to be worked out and take 13.1 instead.

You can not upgrade to an intermediate version of iOS.

You’re welcome.