Unable to populate tick mark on angular checkbox

Question

I have angular code something like this: and I want to populate checkbox ticked for the option which are default selected

export class InformationComponent implements OnInit{

dataIds: FormControl;
@Input()
requestBody:Request;
requestForm: FormGroup;

constructor(private _formBuilder: FormBuilder){}

ngOnInit(){
 this.dataIds =  new FormControl(this.requestBody.dataIds);
 this.requestForm = this._formBuilder.group({
 dataIds: this.dataIds;
 })
 
}

}

<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.7.5/angular.min.js"></script>
<form [formGroup]="reqForm" #mainForm>
 <div>
   <app-data-list [dataIds]="dataIds" [disabled]="disabled"> </app-data-list>
 </div>
</form>

and below is my app-data-list component

export class EntityListComponent implemments OnInit, OnDestroy{

@Input()
public disabled:boolean;
public entitiesFilter:FormControl =  new FormControl();

protected entityList = new RequestEntity[];
@Input()
public dataIds:FormControl;

@ViewChild('multiSelect', {static:true}) multiselect:MatSelect;
protected _onDestroy = new Subject<void>();

public filteredEntityList:ReplaySubject<RequestEntity[]> = new ReplaySubject<RequestEntity[]>

ngOnInit(){
 this.myservice.getData().subscribe((resp:RequestEntity[])=>{
entityList = resp;
})
this.filteredEntityList.next(this.entityList.slice());
this.entitiesFilter.valueChanges.pipe(takeUntil(this._onDestroy)).subscribe(() => { this.filterEntitiesList();});
}

ngAfterViewInit(){
this.setInitialValue();
}

setInitialValue(){
this.filteredEntitiesList.pipe(take(1), takeUntil(_onDestroy)).subscribe(() => {
this.multiSelect.compareWith =(a:RequestEntity, b:RequestEntity) => a && b && a.entity == b.entity;
})
}
}

<div [formGroup]="form">
  <mat-form-field>
    <mat-label> Data ids</mat-label>
     <mat-select [formControl]="dataIds" [multiple]="true" #multiSelect [disabled]="disabled">
       <ngx-mat-select-search [formControl]="entitiesFilter" placeholderLabel="Search">
       </ngx-mat-select-search>
       <mat-option *ngFor="let entity of filterdEntitiesList |async" [value]"entity"> {{entity?.entity?.entityName}} </mat-option>
     </mat-select>
  </mat-form-field>
</div>

but my code is not pre populating the checked option against selected dataIds from back end but I had similar snippet in my code which does exactly same thing