Not only is it trivial, but a number of smart contracts support "flash loans", allowing users to receive a temporary loan of a large amount of cryptocurrency so long as it can be proven that it will be paid back immediately through other contracts. They're a common tool in smart contract exploits.

Tiny nitpick: aiui, it isn’t so much “if it can prove that it will pay it back immediately” so much as, if it doesn’t pay it back immediately, then all the changes in the transaction don’t end up actually happening, with the only consequence being that some gas fees were spent. So, it is as if the loan is retroactively revoked if it isn’t paid back within the same transaction.