I\'m trying to do this, but is looks like it is only possible to change it to primary or warn.
You may use this:
::ng-deep .mat-checkbox-checked.mat-accent .mat-checkbox-background, .mat-checkbox-indeterminate.mat-accent .mat-checkbox-background, .mat-accent .mat-pseudo-checkbox-checked, .mat-accent .mat-pseudo-checkbox-indeterminate, .mat-pseudo-checkbox-checked, .mat-pseudo-checkbox-indeterminate {
background-color: red !important; /* Red background for example */
}