I think you are asking if you can put your card into a credit balance over your credit limit by putting funds onto it.
Technically you can do this however different banks and issuers handle this differently. The main issue is if your card is lost or stolen and used without your permission, the bank MAY not cover you over your credit limit if you have charged up your card as this could be seen as a potential fraud.
Lets say you have a $5,000 limit and a zero balance and you drop another $5,000 onto the card giving you a $10,000 available balance. You lose the card and the thief maxes out your card and spends $10,000. Scheme rules state that you aren't liable for charges on your card that aren't yours.
Does the card issuer cover you for the $5,000 limit that they gave you OR the full $10,000? I think the answer is pretty obvious.
Whilst many here have done it, my recommendation would be to have a card with an appropriate limit in the first place.
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