GGB VAT in the Kingdom is administered by the Zakat, Tax and Customs Authority (ZATCA), which sets the registration thresholds and the e-invoicing requirements a restaurant point-of-sale has to meet. The rate and thresholds are published by ZATCA and change by regulation, so confirm the current position there. What matters for the model is that VAT sits between the menu price and your revenue — cost the menu net of it, never gross.
From Saudi Arabia Restaurant Licence Cost: Every Fee, Explained — the full reading, with the method behind this answer.