Leaving every payment method open on every order looks generous. In practice it is what makes certain orders lose you money.
A cap on cash on delivery
A high-value COD order is a double risk: possible refusal at the door, and round-trip shipping on an expensive item. Set a cap proportionate to your average basket.
Excluding regions
Some remote regions cost more to ship to and have higher refusal rates. You can exclude them from cash on delivery while keeping electronic payment available.
A minimum order value
A twenty-riyal order carrying shipping and a gateway fee can end up with negative margin. A minimum protects against that — but keep it reasonable and state it early, not at checkout.
Restricting BNPL by value
The BNPL fee on a small order can swallow its margin. Most providers already have a minimum — make sure yours aligns, so customers do not see an option that is rejected when they click it.
The governing rule
Every restriction must be visible before the payment step. A restriction that surprises the customer at the last moment costs you the whole order, not just the difference.