Depends on the wallet. It most likely will use your selected coins to burn them with the mint and get the exact amount to send on to the receiver. No wallet that allows you to overpay as of now, afaik. But some devs are debating that option for improved privacy. I love the idea.,
Discussion
Ah, so sacrificial sats for privacy. This is not a bad idea.
Okay, I like this more than custodial lightning. Thanks for the info!