Can I add multisig to an existing wallet

So I’ve setup a wallet and started using some DeFi apps like Aave and Uniswap. Now I’d like to add multisig to my wallet for additional security. Is it possible to add multisig long after the wallet has been created and used?

I paid the hefty fees to deposit funds in the DeFi platforms so I don’t want to transfer everything to a new wallet.