Have you built a content calendar before?
While a junior-level social media role typically doesn't manage their own content calendar, a senior level role will be expected to contribute to ideas several months out. If you've built and executed a quarterly or annual content calendar, even if it was for blogs, videos, or email marketing, your planning skills will easily transfer into social media. This is also a good jumping-off point for talking about your strategic process.
"In my last job, the Marketing Director would establish a strategic narrative every quarter that we would execute across multiple channels. I was responsible for conveying that narrative in social media and preparing and executing a quarterly content calendar to support it."
