Onee way to find this out is that you try before asking. I have a plugin wich support horizontal and vertical scrolling, but currently I am on mobile. If I come at my home then I will try to search into the sourceCode how do I made it, because currently I forgot it. I think it was something like this here, but it‘s 99% wrong:
scrollframe:GetPropertyChangedSignal("CanvasSize"):Connect(function()
scrollframe.CanvasPosition = Vector2.new(scrollframe.CanvasSize.X, CanvasPosition.Y)
end)
But you atleast why your function dosen‘t work, if not I will try to explain it to you:
My theory is that, you know that you can write a 30 long string, but if you have TextScalled to true it won‘t work, because it scales the text so small that it can fit into the textbox. Your string fits into the textbox, so your code is working, just that because it‘s fitting into you don‘t notice the sizechange, because it dosen‘t change. I have the solution, but I am actually on mobile, sorry. I made a plugin, you can try it out say if it‘s that what you are meaning, because I don‘t understand exactly what you want to achieve:
EDIT:
Just saw the video, ok now I understand