EVA Air provides passengers with the option to bid for an upgrade through their Bid for Upgrade program. Travelers can place bids online, specifying the amount they are willing to pay for a premium cabin, and successful bids offer an opportunity to enjoy enhanced in-flight amenities. Bid acceptance is subject to factors like route, seat availability, and the competitiveness of the bid. For the latest information, it’s recommended to check EVA Air’s official website.