Yes, airline websites will often access an IP address (the string of numbers that identifies a computer’s location and connection to the web) in order to provide accurate location-related information like language, proper currency, and relevant deals.
Because airlines are able to adjust their prices in accordance with a specific market’s makeup (business vs. leisure travelers, relative wealth), some believe that changing your IP address using a VPN (Virtual Private Network, a software program that essentially routes a computer’s internet connection through a different location) will unlock cheaper fares. But, as this 2019 New York Times investigation shows, results can vary depending on the airline, route, and the countries involved.