Our income is from commission from our service to transaction between two parties, the buyer and seller. So, because we need to record all their transactions in our Sales Order Lines, we need to create a field called Service Charge/Commission on invoicing.  We see Discount is possible, but how to add Service Charge/Commission in one line based on the transaction?  Is that possible in Odoo v15, or in the future versions?

For example, we record in Sales Order transaction subtotal 1000 USD, and our service charge (commission) in invoice is 10 percent, or 100 USD. If Discount is possible, can we have Service Charge/Commission in standard model also?  Thanks