Is there a single best way to make drop shadows that adapt to the parent frame without manual adjustment?
Roblox should really really implement a UIDropShadow element or something similar. (also ui blur i beg 
)
If anyone has any info, do let me know!
What do you mean by “manual adjustment” – does the shadow become inaccurate when the frame is resized?
Besides an official implementation like you’re suggesting, a decent way to show a drop shadow is to secretly use two sibling frames that adopt a hidden parent’s exact size (with UDim scale set to 1) and lowering the drop shadow’s frame to be below the main window.
Not truly a drop shadow effect (more like glow), but I prefer to use UIStrokes, set them to black, and have a Thickness value between 1 - 1.8, and a Transparency value between 0.4 - 0.95.
This doesn’t scale well with larger screens (since UIStrokes’ Thickness only uses pixel units), but at least I don’t need to upload my own drop shadow image, and it’s the fastest to do for me.
It requires a bit of manual adjust I guess, but just take the instance, clone it, parent it to itself and set the position to -0.1, 0, -0.1, 0, (you can change this as you like) change it to black, and then put the transparency as you like
other than that you could make your ui elements in some external source and then add a drop shadow there