Unknown gesture I want to figure out

I was holding my phone and doing something else and when I looked at it, it had gone to a screen with all 5 of my home screen pages displayed at once, 3 on top, 2 below. How did I get there? I tried holding on a blank spot and it brought up something close, but all the home screen pages were displayed horizontally with swiping. How did I get to that page with all 5 of my homescreen pages displayed?

LG K7 5.1.1

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