Hi Hashem,

I hope you are doing well

Odoo19 deafult comnfigurations you need to use

if community version then Go to Invoicing app -> configuration -> settings 

Enable both option same if you are using Enterprise version Odoo19.

No need customisation

https://www.cybrosys.com/blog/how-to-add-a-payment-qr-code-to-invoices-in-odoo-17-accounting

Thanks you. 

Odoo 19 allows QR codes in reports using QWeb. To add a QR code to your invoice:

1. Activate Developer Mode.

2. Go to Settings → Technical → User Interface → Views.

3. Search for invoice report (account.report_invoice_document).

4. In the QWeb template, insert something like:

<img t-att-src="'/report/barcode/?type=QR&value=%s' % invoice.name" width="120" height="120"/>

You can change invoice.name to the data you want encoded (payment link, invoice URL, IBAN, etc.).

1. Save, upgrade cache, and print your invoice.

This will automatically generate a QR code on your invoice.