In order to customize the appearance of your collection at the contract-level, you can implement the contractURI method in your ERC-721 or ERC-1155 smart contract.
contract MyCollectible is ERC721 {
function contractURI() public view returns (string memory) {
return "https://metadata-url.com/my-metadata";
}
}
This URL should return data of the following format:
{
"name": "OptiPunks",
"description": "10,000 unique collectible characters with proof of
ownership stored on Optimism",
"image": "https://www.optipunks.com//image.png",
"external_link": "https://www.optipunks.com/",
"seller_fee_basis_points": 250,
"fee_recipient": "0x6E9540950B46c35C7C419e57eF6dc6F946B95338"
}