I downloaded the message app as requested to help “communicate “. I have an iPhone. When typing the message there is no way to minimise the keyboard and so there is no way to send the message. How am I supposed to use it?
It has been a while since I've used an iPhone, but from a bit of a google search I recommend you try the below tip.
To hide it, slide your finger down from above the text-entry box and the keyboard will start to disappear. Carry on until only the text-entry box is left. To make the keyboard reappear, tap the text-entry box and it will shoot right back up so text can be entered again.