There is no general size limit on ligatures, no. What gave you the idea that there was?

If you're using a typeface that is designed specifically for text sizes, you might be inclined to track it more tightly at larger display sizes. In such a situation, the spacing of the ligature might start to look oddly loose next to the rest of the spacing. In such a situation, you might need to break apart the ligature. (An app such as Adobe InDesign will do this itself automatically, assuming the ligature was formed automatically in the first place.) Personally, if I found this necessary, I'd make sure that the typeface wasn't getting nasty collisions as a result.

There are plenty of typefaces with optical size variants or otherwise designed for display sizes, which have ligatures. This includes many or most of the Adobe Originals, for instance.

Regards,

T