Just a curiosity

I saw someone saying on a YouTube comment that we get to see How Frieren Learned that spell from The Height of Magic. Is that true? If so, in what chapter It is?

Normally i would ignore It cuz It seems like some dumb people's theory, but i stopped Reading the manga at the beginning of the corrent arc so i fear that If It's True, Not Just some dumb conclusion from someone who doesn't pay attention. Like the one Guy in the Same comment Session saying Because Clone Frieren used that spell on Fern, Fern must be as Powerfull as The Demon King.

Edit. It was dumb of me to even get curious about It. The person who Said It was the Same person who Said Fern was strong as The Demon King cuz clone Frieren used Height of Magic spell on Fern. Should've known by then.