No, that's for small aircraft and their postwar era engine designs. To give you an idea of how slow development is in small aircraft engines, AVGas (Gasoline for airplanes) is still leaded.
That’s more because of how old the fleet is. Modern engines with fuel injection, electronic ignition, turbos, and (optional) constant speed props don’t really care as long as their ECU has a map for it.
Manufacturers are actively prohibited from this activity by US antitrust law. The “United” in “United Airlines” was a reference to the joining of Boeing and Pratt&Whitney.
Although aircraft are designed for specific engines, it’s up to the customer to execute a separate purchase agreement for them.
