It is impossible, when you try to send bitcoins to another address, and you suddenly have a typo mistake, the wallet provider is going to show you that address as a wrong one.
That is why it is almost impossible to have that kind of mistake, because the transactions that have been sent to wrong addreses are never sent.
Probably, there is one chance in one hundred to send bitcoins to another address that already exists.
maybe the addres is xxxxxxxxxxxx1, and you change that 1 to 2, and it can send it, but it is just that, one chance in a hundred.
Actually in Wallet Import Format (WIF) there are four bytes that serve as control bytes, so if you change one or more address letter by mistake you would need to correctly change the 4 control bytes too, and for it to happen by chance the probability is not 1 to 100, but
1 to 4,294,967,296 which is rather impossible.
But you may copy-and-paste a wrong address. That is definitely possible. I copy and paste wrong info all the time (thankfully it never happened with the bitcoin address and I hope it never will)