I currently use KM for text expansion on my laptop and would like a way to have the same options on IOS. I have a lot and they are always in flux. Ideally it would use some type of plain text file that would get updated by a KM and than said file would be synced using iCloud drive, dropbox, ect. Any advice would be appreciated.
TextExpander is cross platform.
To use it in any app on iOS/iPadOS, you can use the software keyboard.
Some apps also have built-in TextExpander support (TextExpander enhanced apps), and you can use any keyboard, including physical ones, for those apps.
Don’t forget Apple also has keyboard text replacement for basic replacement needs, and that works a ross all apps and keyboards on the Apple platforms.
Hope that helps.
Here’s how I do it with Alfred and the last ore-subscription version of TE (still working on Big Sur).