If you applied to an elite program at CU Boulder, such as Engineering or Leeds School of Business, you may eventually be admitted to that program or admitted to the College of Arts and Sciences, from which you can take relevant courses your freshman year and demonstrate you can handle college level work in that field; then, reapply to the program for your sophomore year. They want to see your senior fall semester grades to see how you're doing. If you applied to the College of Arts and Sciences (general application), you may eventually be admitted, but they want to see your senior fall semester grades.
You can submit a Letter of Continued Interest to let the college know you are still VERY interested! (Or go here for tips).
You can submit "late documents," which are materials reflecting achievements you have earned since you submitted your Early Action application in November. These can be for things like a promotion at work, lettering in a sport, making it to State in DECA or something similar...positive updates to your "resume." Colleges are generally happy to include these updated materials in your application file.
I don't know if you will hear a final decision about admission before 4/1/24.
Start making sure you have alternatives. Other great alternatives on the Front Range include CU Denver, University of Colorado Colorado Springs, University of Northern Colorado, CSU Pueblo, and Metro State University of Denver.
If you are very interested in this college, you can accept a position on the waitlist. Nationally, 10-20% of applicants are eventually accepted. At very selective colleges, the rate is 7% or less.
You can look at a college's Common Data Set (e.g., Google "[name of college] common data set"). Look under section C2 where you can see how many applicants were placed on the waitlist last year and how many were eventually accepted. Examples from Williams College and University of Richmond.
Call the college's Admissions Office and ask if they accept late documents that show achievements you have earned since your application was submitted. If they do accept late submissions, write a letter of continued interest (or here) and list your accomplishments.
You will probably not hear anything about your acceptance from the waitlist until late May, June or even July.