Pre-Select a radio/checkbox: Checked property not working properly

I have a simple question and i have not been able to solve it using numerous solutions. Here is the code.

<input type="checkbox" class="custom-control-input" [(ngModel)]="patient?.InsurancePolicies[0].BillTo"
              (click)="clearFacilityField()" name="billTo[]" id="id" [value]="'sample_value'"
                   checked
            />

This checkbox doesn't get pre-checked. I have also tried giving a value to checked, i.e. checked="" or checked="checked" but this also doesn't work.

Ps: I know this is a trivial issue but i have been stuck on it for a long time now.