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*/
}