예뻐진 여자 is actually past tense because adding 지다 turns it into a action verb . If you use 은/ ㄴ instead of 는(present tense) it will indicate a past state. So 예뻐진 여자 is a girl who has already become pretty. 예뻐지는 여자 is a girl that is becoming prettier and 예뻐질 여자 is a girl that will become pretty. So use the verb+ ㄹ/을 +noun form to show future tense noun modification.