No, as of right now it is not possible to make a QR code that directly adds a chain natively.

What you can do is create a QR code to a data: URL containing a code that calls wallet_addEthereumChain.

The HTML code:

<script>
    ethereum.request({
        method: "wallet_addEthereumChain",
        params: [
            {
                chainId: "0x64",
                chainName: "Gnosis Chain",
                rpcUrls: ["https://rpc.gnosischain.com/"],
                nativeCurrency: { name: "xDAI", symbol: "xDAI" },
                blockExplorerUrls: ["https://blockscout.com/xdai/mainnet/"],
            },
        ],
    });
</script>

The data URI (made with https://dopiaza.org/tools/datauri/index.php):

data:text/html;charset=utf-8;base64,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

And then made into a QR code: