Will 20X8.5 wheels fit Lexus ES330 ?

Yes an 8.5 will fit width wise, however the largest aftermarket wheels recommended for a Lexus ES330 2004-2007are only 19" so you may still have some issues with rubbing your tires with the 20" rims. In any case the jump from the 16" factory wheels to 20" wheels is going to cost you in gas money.