Which two specific methalox engines are cited as examples of the next wave of heavy-lift, reusable launch vehicle technology?

Answer

Raptor and BE-4

The text specifies that the Raptor engine used by SpaceX and the BE-4 developed by Blue Origin are explicitly designed around methalox chemistry for future launch systems.

Which two specific methalox engines are cited as examples of the next wave of heavy-lift, reusable launch vehicle technology?
fuelrocketpropellantcombustionMethane