I see this posted almost every day. Somebody wants to protect their seed so they go through an incredible amount of effort to encrypt it in a file and remember the password. Or they resort to some home-cooked method of splitting their seed or hiding one of the words.
I get it, keeping those 12-24 words laying around for anyone to read can be dangerous. Adding extra protection makes sense.
Here's the thing: The BIP39 seed standard already has built-in support for what you want to do. It's called the "passphrase". Not only does it allow you to keep your seed away from a computer, it's also supported by wallets, including hardware wallets. They also provide plausible deniability in the event you are forced to unlock your wallet.
Please do research and use the passphrase method instead of resorting to home-cooked seed storage solutions! Take your time, do a practice run with a small amount etc. But keep your seed away from any computer.