disable mat radio button outer circle

    :host ::ng-deep .mat-radio-container{
      height: 10px;
      width: 10px;
    }
    :host ::ng-deep .mat-radio-outer-circle{
      height: 10px;
      width: 10px;
    }
    :host ::ng-deep .mat-radio-inner-circle{
      height: 10px;
      width: 10px;
    }
    :host ::ng-deep .mat-radio-button .mat-radio-ripple{
      height: 20px; /*double of your required circle radius*/
      width: 20px;  /*double of your required circle radius*/
      left: calc(50% - 10px); /*'10px'-same as your required circle radius*/
      top: calc(50% - 10px); /*'10px'-same as your required circle radius*/
    }