App scaling blue bubble button

[mattchoo]

I saw on YouTube where you can trigger this button took come out in app. I couldn't make it appear. Any idea? LG G6+

 

[dsscolumbia]

I think it only appears on apps that are scalable.

 

[mattchoo]

I think it only appears on apps that are scalable.

yeah. Think so too. Even those listed, not necessary work too. Oh. Activation of the button i  n app is pull notification bar down.