How to know if offer comp is off market

I’m still interviewing but I’m wondering how I’ll know whether the compensation package a company may offer me is not off market. Are they doing anything to ensure their salaries are in line with competitors? Thanks

Basically companies hire HR consultants who are in constant communication with different firms in the same industry to get an idea of the how much competitors are paying people in similar roles. They actually compile a grid of overall compensation (base + bonus) with min/max salaries corresponding to each position/title. Also, these companies may also use these HR consultants to hire candidates and help negotiate their compensation packages.