How to Find Sponsors or Brands Interested in Promoting Through You, I will not promote

As I was looking for sponsors for an in-person event, I realized that many companies and organizations either don’t respond or just see the message and don’t reply. I reached out to both small and big brands, offering to promote their products or services to my Gen Z audience (59K followers). I only contacted brands with similar audiences to ensure alignment. Is there something I’m doing wrong? How can I improve my approach to get better responses?