flow emulator startflow project deployflow transactions send ./transactions/setupAccount.cdcflow transactions send ./transactions/mintNFT.cdc 0xf8d6e0586b0a20c7 "Example Name" "Example Description" "Random CID" {}
The account with the Administrator resource would use the transactions/updateNFTMetadata.cdc transaction to do this. You pass in the NFT's id (that you would get from Rarible events or something like that) as well as the current owner of the NFT, and pass in a new name, description, thumbnail, and metadata dictionary. This will automatically update the NFT owned by the current owner with the specific id to that new metadata.
There is a Minted event in the contract you can track to see when an NFT is initially minted. It looks like this: pub event Minted(id: UInt64, by: Address, name: String, description: String, thumbnail: String)