Franchise Related SEO dilemma

I am a franchisee in National retail business who has a main website for the entire franchise and locations are all on the main domain.

To put it bluntly, the SEO and web development on the domain is horrendous .

I’d like to go ahead and start my own domain for my particular location, but I’ve heard that this might not be a good idea as it will confuse Google and result in a decrease in my local business listing .

My question is if I wholeheartedly believe that my location specific domain can crush the existing Landing Page on the main franchises website should I embark on this journey?

Keep in mind that this Franchise website is about 15 to 20 years old .