Take it from someone who worked with luxury brands multiple times: these brands are a bit different than the mainstream ones. These brands work more on brand association basis rather than target audience. This means that the first thing they'd look at once you propose a collaboration with them is who you are being. In other words...your personal brand. Starting from your content aesthetics to your own style and in what ways you actually embody the values of that brand. So being a good fit for the luxury brands of your dreams is the ONLY thing you need to worry about.