If only it were that simple. Simply put, it's impossible. Or do you think that staking rewards are being charged to you out of thin air? Staking is the provision of liquidity to a protocol, which earns on your provided liquidity and gives you a percentage of those earnings. That is, roughly speaking, you are giving away your money for rent.
Staking from cold storage is like trading on a centralised exchange, but keeping your money in a cold wallet