Could mRNA vaccines be designed to provoke the body into generating antibodies like this on its own? With the existing mRNA vaccines, they took mRNA that corre

Could mRNA vaccines be designed to provoke the body into generating antibodies like this on its own? With the existing mRNA vaccines, they took mRNA that corresponded to a stabilized form of the spike protein. Could you work backwards instead, where you know the kind of antibody you want to generate, so you design an antigen that only that antibody would bind to?