You can utilize Angular's Date Pipe for it
Have attached a Stackblitz Demo for your reference
import { DatePipe } from "@angular/common";
@Component({
  selector: "my-date",
  templateUrl: "./date.component.html",
  providers: [DatePipe]             // Add DatePipe as Provider
})
export class DateComponent {
  now: any = Date.now();
  format: string = "medium";       // more formats are available inside the DatePipe Documentation
  constructor(private datePipe: DatePipe) {}    // Initialize DatePipe inside the constructor
  get dateInGMT(): any {
    // 1st parameter is the date
    // 2nd parameter is the format
    // 3rd parameter is the time zone
    return this.datePipe.transform(this.now, this.format, "GMT");
  }
  get dateInCEST(): any {
    return this.datePipe.transform(this.now, this.format, "CEST");
  }
  get dateInCustom(): any {
    return this.datePipe.transform(this.now, this.format, "+0530");
  }
}
You can also do it like this:
medium is a format and CST is the timezone or you can supply any values you want.
<pre>{{ now | date: 'medium' : 'CST' }}</pre>