How to Leverage Brand-Specific Subdomains to improve SEO?

One of my clients is looking to drive traffic to a niche sports store located and operating in the United States.

What is your feedback on the following: Does it help to have the domains secured for Brands within the sports industry they sell? So if we register five subdomains and all are the names of Brands they stock will that help with SEO campaign?

For example, if the stored brands are x, y and z and now secured the domains of all three so x, y and z are worldwide brands and well-known ones.

The question is will securing those domains be beneficial? and if yes how can they be used for the best SEO practices?

Grabbing brand-specific subdomains can work if you populate them with solid content that’s all about those brands. Just using the names isn’t enough; it’s the relevant, unique content and user engagement that’ll make the difference. Connect these subdomains with your main site properly to boost overall domain authority.

Short answer: only use subdomains if you have some good reasons to do so. While they profit from the main domain, Google treats them a bit like separate domains. Means more work, diluted SEO efforts, it's almost like optimizing totally different websites.
So, if you can use subdirectories instead, e.g. for different countries, it's a lot less headaches.