@thumper1 's advice is probably correct for most ‘non-specialized’ colleges, but the OP was asking about a portfolio in this art-school forum. (not a supplement)
For art schools, portfolios are very important and to some degree I do believe a very good portfolio will offset lower range GPA and/or scores.
As I’m sure you know, there are National Portfolio Days where you can get feedback on your work from AOs from the art schools. They can probably provide good info on chances.
good luck.