It would be useful to have the option of keeping a fixed line thickness when scaling. Proportional scaling as it is is great and very useful, but it would be good to have both. Say you have made up a bunch of graphs and saved them as stickers, you don't want the line thickness of the axes to scale with the overall size of the graph. I would find this feature useful in iOS/Mac as well.

(If it's a headache to implement I'd rather GoodNotes stay unbloated.)