@MWolf’s correction is nevertheless true. At the PhD level, music theory is often separate from composition (or piano) and the requirements MWolf detailed are what you would pay attention to. I am not sure about DMA requirements for music theory.
@sackblake it is still early in your schooling, and we don’t know much about you. If you instead move more toward composition, then submitting pieces will be important.
The job market for faculty in humanities is terrible and has been getting worse in recent years. COVID has decimated music, at least for now. Adjunct positions don’t pay well and even those are hard to get. Many faculty do what is essentially piece work, paid per class per semester.
Many doctoral students work between undergrad and grad, or between grad and doctoral. There are doctoral students in their 30’s or older in some cases.
Follow your dreams for undergrad. Music majors have access to different jobs and med, law, business, nursing and other grad schools. Once you graduate, reassess and stay flexible!