I don't think there is a limit to how many apps icons can be in an iOS folder, they're paginated. Right now, I have 27 in an "Apple" folder, spread over 3 pages

I don't think there is a limit to how many apps icons can be in an iOS folder, they're paginated. Right now, I have 27 in an "Apple" folder, spread over 3 pages. If I add another icon, it adds another page.