mint Free & paid

Free mint <=3 & pay x value if mint >3

 function mint(uint256 quantity) external payable {
        require(totalSupply()<=maxSupply , "Minting Ends");
        require(quantity <= maxMinting , "Minting need to be less then 3");
        uint userMinted = _numberMinted(msg.sender);
        
        if(userMinted >=3 ){
               //pay if user has 3 free mints
               require(mintPrice * quantity >= msg.value, "Ether value sent is not correct");
               _mint(msg.sender, quantity);
        } 
        else{
               //free if user has not minted yet
               _mint(msg.sender, quantity);
        }
    }

msg.sender

_mint(msg.sender, quantity);

wallet address of contract invoker

msg.value

require(mintPrice * quantity >= msg.value, "Ether value sent is not correct");

wallet address who tries to mint with bigger or equal to the value being signed.