@dlx aha, now i know what you mean, thank you. I think you can create the modifier yourself, with frame(width: 0).:
Color.blue
.frame(
minWidth: 10,
idealWidth: 150,
maxWidth: 300,
minHeight: 20,
idealHeight: 100,
maxHeight: 300
)
.frame(width: 0)
PS: pardon me, I never played with fixedSize + frame with min and idealWidth, mostly with Text or HStack.