KLM allows passengers to move to the next higher class cabins using the upgrade options. It allows them to request an upgrade with available methods, such as using miles, paying in cash, or placing a bid. If travelers request a KLM Upgrade to Business Class, they can get different benefits, such as bigger seats, priority services, or food options. To learn more about the upgrade on the airline, one can contact the KLM customer service team or go through the blog at the mentioned link by Airlines Group Travel.