>>7662131
I use pinterest and bing, unironically.
I searched for shoe references on bing, found something I liked, turned out it was a pinterest pin and that redirected me to this x profile that's full of shoe references https://x.com/radenwa_tweet
If you don't have a twitter account, you can just replace x with xcancel in the url.
There are also neat references and tutorials on pixiv and just about any other art site, but using bing is usually faster for me if I already know what I'm looking for.
You could probably try 3D models too but I don't think they're on par with drawn or photo references.