At least in the US, to "look like a scarecrow" would be the most common idiom that is widely understood. Some examples going back to at least 1905:
I'm really sick of all these actresses looking like birds... I'd
rather look a little chubby on camera and look like a person in real
life, than look great onscreen and look like a scarecrow in real life.
- Actress Jennifer Lawrence, 2011
Like all the people in the loft she dressed like a hippie, and being
so skinny her loose-hanging clothes made her look like a scarecrow
swaying in the wind. - Kokis & Wilson, The Art of Deception: A
The lad grinned sheepishly, and began to hustle into his garments.
They were a world too large for him, and hung upon his shrunken limbs
in a baggy and outlandish fashion. His shoes were ten sizes too big;
his cap rested upon his shoulders. "Huh!" he muttered in disgust. "I
look like a scarecrow." - James Ball Naylor, "The Little Green Goblin
of Goblinville, 1905.
So the idiom goes back a while but is still in use in popular culture today.