Who own's a franchise's social media account? The parent company or the franchise owner?

Let's say that I start a McDonald's franchise and create social media accounts for my specific location to engage with my customers.

Who would own those social media accounts? I, as a the franchise owner and creator of those accounts, or does the parent company retain all rights?

It probably depends on the franchise setup and rules (what your franchise license buys you). Franchise would own a trademark for their name, so if you created an account using it, e.g. [official name + anything] they could force you to give up that account name if they thought it was creating unfair competition for other franchise owners (if you use location in the name that represents multiple owners).

I am not a lawyer, so always best to consult a lawyer but review the franchisee agreement (first).