As Charlie said, you should be at least a Level-II Thermographer to undertake this job. If it’s for insurance purposes, as most of these jobs are, the insurer will almost surely specify a Level-II minimum qualification. You absolutely, positively must have the appropriate electrical safety qualifications too (OSHA), not to mention insurance for commercial thermography.
As far as bidding commercial electrical inspections, the square footage doesn’t really matter very much. What matters is how much and what type of electrical equipment is in scope, whether you are documenting all equipment or exceptions only and who is providing the electrician(s) to strip and recover enclosures. I did one that required 800+ pages to document.