Swiss QR Bill Management for NAV 2018

I don't think so, that version it's some years earlier than requirement. In BC I think it's done.

In the article below they mention it's required in Switzerland since 2020, so I assume it's also been added in the BC version of that period and those afterwards.
https://docs.microsoft.com/en-us/dynamics365/business-central/localfunctionality/switzerland/ui-extensions-qr-bill-management

You can look through the CU's of 2018 to see if it might have been added anywhere.
https://support.microsoft.com/en-us/topic/released-cumulative-updates-for-microsoft-dynamics-nav-2018-c469ba91-ee7a-ec06-e72a-6c8e331ea978

Otherwise if you want it, you'll have to look through the BC source code and add it to 2018 yourself.
Or upgrade the client to BC !