Although writing about your future career goals may not be a mandatory part of your graduate school statement of purpose (SOP), graduate school admission committees still find this information relevant and meaningful. For instance, they learn not only about your motivations, but also your future aspirations dovetail with what the program offers or can offer. Moreover, being able to detail your future plans demonstrates to the committee that you’re capable of thinking over the long term, which shows focus and determination.
Therefore, it’s important to be able to explain what exactly you want to do with the degree you wish to earn. To be honest, many admissions committees want to see that an applicant wishes to continue in academia, whether that’s a PhD, a post-doc, or tenure-ship. After all, academia is set up to produce more academics, whether that’s professional development for writing CVs, applying for grants, or presenting at conferences. So even if you are not planning on continuing in academia, it might make sense to say that that’s your goal anyway!

On the other hand, it doesn’t hurt to also mention your real plans or your back-up plans. For instance, I did a master’s degree with an English department, and my real career goal is to set up a full-time freelance academic editing business. I do also want to get another master’s degree, but not in the same subject. My program didn’t offer internships with publishing houses or do any work specifically related to editing or running your own business. Still, academic editing usually requires a graduate degree, so it made sense for me to mention how a master’s degree with an English Department would help my future career goals. For you, it might be working in a research lab or a community organization focused on social justice. Whatever you hope to do with your degree, I would encourage you explain how the degree you’re applying for will support your future goals.