Elias here with Shopify Support. Thank you for reaching out.
I understand you’re looking to edit your logo size on the mobile view on the Brooklyn theme. If your store is subscribed to a plan, this is something that our Theme Support team can help with. That said, you can have different logo sizes between mobile and desktop. I’d be happy to send this request over to them and I can update you with a support ticket. Before we go ahead with this request, could you clarify what size you would like your logo?
Feel free to share a screenshot of your preference with me, looking forward to hearing from you!