Do you think this niche will work as a Instagram influencer

theres potential, but this does already exist and is getting popular

I follow a few accounts like this. As you want to monetise on the fashion side, I think the key to having the most growth and impact is through maintaining a very visually aesthetic grid, but also try to throw in something that separates you from similar accounts. I often stumble across these accounts through the recommended section and explore page but notice that a lot of these pages are sooo similar that it doesn't make sense to follow more than a handful. Also engage with people in the comments so that you build trust with your audience, making them more open to buying what you offer. Good luck!