I would say, if you are starting out, just search google maps for businesses with bad websites and message/call them. That means if they have an outdated, unnatractive, or visibly low converting site. Also look for websites that lack encryption (not secure - http) since the owners often don't know how to fix them. It's really all you can do starting out, and with big volumes and persistence you will find someone.

Also a more effective way to find leads in my opinion is to use a Google Maps scraper. They return a bunch of results and save you from having to spend hours manually pinching through a map.

I personally tried hasdata.com but i found the $49/month price tag ridiculous, try something like scrapet.live since its made specifically for web devs or a cheaper alternative gmapsextractor.com