How do I do competition research for non.com sites?

Hey guys, a local tailor here in NY expressed interest in getting some basic SEO done on his Wix site. Upon searching google for the 3 keywords he gave me, the top 3 local pack listings ll have different domains, the first links to a Facebook page, the 2nd and 3rd links to .business.site.

When I put the domains of those 3 websites links into Semrush's competition research it is showing some out of this world stats, like 'billions' of backlinks and 100 Authority score so that too I don't...

How do I do competition research for non.com sites? WordPress ...