iPhone 6 - apps won't load or update!

This is an impasse.

Your iPhone is limited to iOS 12 and incapable of running later iOS versions, and that app requires iOS 13.

Your options are a newer used, refurb) iPhone, or a new iPhone.

And for completeness, no, there are no hardware upgrades available.

Hi AnneinFl,

We understand you're having trouble downloading and updating apps on your iPhone. Do you get an error at any point when attempting to do either? Check out this article for a few steps to try in this situation: If you can't download or update apps on your iPhone or iPad.

Test out the behavior while connected to another network. If you're connected to Wi-Fi, try over cellular data or another Wi-Fi network.

Ensure that you have sufficient available space: How to check the storage on your iPhone, iPad, and iPod touch.

You may need to update your software if it's outdated. Be sure to create a backup before updating your iPhone. These articles will help:

How to back up your iPhone, iPad, or iPod touch

Update your iPhone, iPad, or iPod touch

Cheers!

Your issue is you have a 7 year old iPhone which is stuck at iOS 12.5.4 and your phone lacks the hardware required to update to the newer iOS versions. This is only going to become more common as time moves on. It's time to give serious consideration to retiring your old iPhone in favor of a newer, more modern iPhone.

It's entirely up to the app developers if they want to maintain older versions of their apps for older devices. Many App Developers simply don't do that.

The app update notices that the apps require a version newer than that in use? No.