Hii here is the updated version, that worked for me Angular v18 :)

//setting checkbox size
::ng-deep .mat-mdc-checkbox .mdc-checkbox {
  height: 24px !important;
  width: 24px !important;
  flex-basis: 24px !important;
}  
::ng-deep .mat-mdc-checkbox .mdc-checkbox__background {
  height: 24px !important;
  width: 24px !important;
}

Greetings, thegreyluk