I would like to provide you an answer to this.
Brooklyn theme default supports the transparent header. You can check it by going to Online Store > Themes > Customize > header
You can see my screenshot here https://prnt.sc/tmxyvp
I provide a guide to improving the store's home page, you can check it here.
I hope my answer will help with your issue. Like it, if you feel it is helpful or mark it as a solution.
Let me know if you have any questions. Cheers!