Question is, Is there a way to get the values expanded from a quantifer?

No. But maybe variable interpolation helps:

echo 123.45.67.890 | perl -ne'$ip = join ".", ("(\d{1,3})") x 4; /^$ip
+$/; printf ...'
[download]

Still, you shouldn't be using a regex for this. Consider using split:

echo 123.45.67.890 | perl -ne'printf "%X%X%X%X\n", split /[\.\s]/'
[download]

Btw: 123.45.67.890 is not a valid IP address ;) When you have come to your senses and thought of a valid IP, think about using unpack.

U28geW91IGNhbiBhbGwgcm90MTMgY
W5kIHBhY2soKS4gQnV0IGRvIHlvdS
ByZWNvZ25pc2UgQmFzZTY0IHdoZW4
geW91IHNlZSBpdD8gIC0tIEp1ZXJk