Use of Bitcoin paper wallet
Yes, if someone locates the paper wallet and is able to read the key on it, they can spend any BTC sent to that wallet.

The wallet is secure if used correctly. Paper wallets are usually intended to be stored in a safe place, such as a literal safe or bank vault. They are not meant to be left on desks, dropped on the street, etc.

Additionally, you could utilize BIP38 to encrypt the private key on the wallet with a passphrase, that only you know.

Remember, any system is only as secure as its weakest link. Even a state of the art hardware wallet is useless if your seed word backup is easily accessible by an attacker, since they can recover the entire wallet from that.