Modify user or session when using social sign-on

export const auth = betterAuth({
plugins: [
          customSession(async ({ user, session }) => {
               return {
                    user: {
                         ...user,
                         externalUserId: null,
                    },
                    session,
               };
          }),
     ],
     socialProviders: {
microsoft: {
                    // Deleted the basic stuff here
                    getUserInfo: async (token) => {
                    const response = await fetch("https://graph.microsoft.com/v1.0/me", {
                         headers: {
                              Authorization: 

,
                         },
                    });
                    const profile = await response.json();
                    return {
                         user: {
                              ...user,
                              providerUserId: profile.id,
                              externalUserId: profile.id,
                         },
                         data: { ...profile, providerUserId: profile.id, externalUserId: profile.id },
                    };
               },
          },
}