I know several NROTC mids who have done this, which is what I assume your question was. You'll need to do the pre-BUDS cruise during your rising Senior year (I think it's that year) and do well there. Although a few of the folks I know made it through BUDS they DORed later in the program. A very hard route to go but you'll at least stay in excellent shape while you're on it.
Yes, the pre-buds cruise is a two-week session during the summer between junior and senior year. It used to be called mini-buds. It is now known as SOAS, which stands for Seal Officer Assessment and Selection. It is a very competitive process to be selected to attend SOAS, which is by invitation only. A candidate must fill out an application, submit letters of recommendation, and pass the fitness test consisting of a 500-yard swim, push-ups, curl-ups, pull-ups, and a 1.5 mile run. NROTC and Service Academy Midshipmen are assessed together and compete for a BUDS opportunity.
There are many older threads about this. It’s not an easy path. It can be done. It’s all about prep. Understand the attrition rates. Use the search function. There is a site specific to those training for this community: https://www.sealswcc.com.