Every time you type on the iPhone or iPad keyboard, a little click sound is made. This is default in iOS. This feature helps users to type on virtual keyboard easier but some users find it to be annoying. You can change it easily with a few clicks. After your change the key taps stay quiet.
You can disable the keyboard clicks sound permanently through a settings change. But you want it temporary you can just use mute option.
This change is instant. After your change you won’t hear any sound when you’re typing anything. You can revert this change easily; just flip the switch to the ON position.