I recall that QR only support data up to 3KB, so your option is either.
1. Store the transaction to file and use other means (such as USB drive) to transfer it to the online device.
2. Make several smaller transaction instead, although you pay more for TX fee.
If you're advance user, you could get the raw transaction, split into several parts and use it to generate multiple QR code. On the online device, you need to scan multiple parts and reconstruct the raw transaction manually.
1. Store the transaction to file and use other means (such as USB drive) to transfer it to the online device.
2. Make several smaller transaction instead, although you pay more for TX fee.
If you're advance user, you could get the raw transaction, split into several parts and use it to generate multiple QR code. On the online device, you need to scan multiple parts and reconstruct the raw transaction manually.
The second one is the only one that is feasible if you want to scan the QR code using a hardware wallet.
The first option of storing it in a text format of some sort and using USBs is only practical for desktop wallets or anything else on the PC. Or maybe in the case of your phone having a USB-C port and you can read data from that, but it's not useful for mobile wallets with scan functionality built-in at all.
