You can, but depending on the size of your brand and goals for your social media accounts, an intern can become quickly overwhelmed, as managing social media is more than just curating random posts.
An agency has the manpower to not only define your goals for your brand based on engagement and website analytics, but they can also build out your content calendars around those analytics.
Hiring a social media management agency means you’ll get planned campaigns, data-driven content, community management, reporting, and an unbeatable integration with other parts of a digital marketing team, like PR and SEO.