Add lazy minting feature on NFT Marketplace -- 2

We need a solidity expert to add feature to our smart contract before we deploy it to mainnet (currently MATIC), we need a feature that has capability to lazy mint (gas free mint) in our site. and we do also need to optimize our current contracts to reduce it's contract size. We are using ERC721 and openzeppelin library contract upgradable.

You also need to discuss how you will plan this setup.