Yes. The highest bid when the clock stops wins, and that is the sale.
You do not get to pick a different bidder, and you do not get to decline because the number was lower than you hoped. Can I refuse to sell if the bidding ends too low?
The exception
You can block a buyer from your store. That is about the person — someone who has been abusive, or who has not paid before — and it stops them bidding on your items at all.
Done beforehand, it is a legitimate tool. Done after they win, to get out of a sale, it is a cancellation wearing a different hat and is recorded as one.
So if you have a buyer you will not trade with, block them before they bid, not after. How to raise an issue
If the winner does not pay
Then it resolves itself without you doing anything. The window passes, the win is cancelled, and the item goes to the under-bidder as a second-chance offer or back to you.
That is the normal mechanism and it costs you nothing. What is an unpaid win?
What you cannot do
Sell it to the under-bidder instead because you prefer them.
Ask the winner to pay more than they bid.
Cancel and relist hoping for a better night. This is the one people talk themselves into, and it is the most damaging: it is a cancellation, it is visible to the buyer, and it is the review you cannot undo.
What protects you properly
A reserve, set before. The only legitimate way to refuse a price. What is a reserve price?
An accurate description, so nobody wins something you did not mean to sell as described.
Not listing things you are not ready to part with. Sounds obvious; it is behind a lot of these questions.
Why buyers need this to be true
A buyer deciding whether to bid is deciding whether the auction is real. If a seller can decline afterwards, the bid is just an opening suggestion — and people do not get into a bidding contest over an opening suggestion.
Every rupee your items fetch depends on bidders believing the result stands. That is what this rule buys you.
More: can I refuse to sell if the bidding ends too low, what is an unpaid win, is a bid legally binding.