@bigil It seems this feature is not available in Acumatica. However, on Purchase Orders we do have an action called Create Prepayment Request which uses the percentage set at the Vendor Info Tab to create a Prepayment and apply to the PO, which will be applied to the Corresponding Bill. This is due to the fact we know the prepayment required and percentage of it when the PO is being approved and logged into the system while sales order can come from customer self service portal in which it is being created by customer.

However, this is a great idea for future version despite it was partially implemented for Sales Order and it was shared by our clients almost 8 years ago.

You can add this to Ideas and based on number of votes it may receive our product team decide on adding it to the future road plan.