It depends. Some IM programs only require that you take Step3 in your 2nd year. That's too later for fellowships to even see it. If you apply in your 3rd year, it shows up and you might not even pass filters then at some fellowship places. My program had a transfer from a very selective, very brand name residency in another field. He was AOA, rocked his Step1-2. However, when applying for fellowship, he got much fewer interviews than his resume would indicate and especially versus less statistically qualfied classmates. He figured it was due to his low Step3 score which he quickly took during a busy intern period. No one talks about ERAS filters, but they're there.