At this time, online-only (timed) auctions on Artsy do not support what is known as popcorn bidding, or extended close times on lots with bids that are placed within the last few minutes.
All timed auctions on Artsy close precisely at the exact time listed in the auction description, and the highest bidder will win the lot. As such, we highly recommend that you place a maximum bid as early as possible. This way, if another user bids the same amount as you in the last few minutes, Artsy will automatically give the winning bid to the person who placed their bid first.
Please see “What is a maximum bid?”