Romans 13 opens with instruction to honor governing authority, framing it as part of a broader call to order and civic responsibility. It's one of the more debated passages in scripture — read narrowly, it's a call to lawful order; read in full context, it sits alongside Paul's broader teaching on love and conscience.
On apparel, it's typically used to represent honoring one's country as an extension of faith — not blind obedience, but a recognition of civic duty.