Never heard of this, sorry. Where did you hear about it and what is it supposed to do?
[topic moved to Reader/Acrobat DC for Mobile forum]
What is the version of Acrobat/Reader do you have on your iPad?
Are you referring to the Tool Switcher in Acrobat Reader for iOS (version 15.0 or newer)?
To display the Tool Switcher in Acrobat Reader for iOS, you can
Please let us know if you need additional information.