no, it's wrong . The correct way is :今天你看起来很漂亮/ 你今天看起来很漂亮
今天:today . In Chinese , the words about time, for example :just now , afternoon , 7:00 , we usually put them at first place .and subject often put at first place...like you , me , my mother....
“你看”means: look! means ask someone to see something. “你看起来”means:you look / you look like...it's for the evaluation of others.