Set up theme and default locale(localization) in keycloak 21

How to set default theme and default locale of master realm keycloak ? I want to set the theme and locale at start-up of the keycloak-server. i dont want the user to go and manually chnage them in the settings. I can get the job done using admin API and make PUT call using java. However, is there an easier way to get it done, may be by passing some key:value pair ?