See: https://learntech.imsu.ox.ac.uk/blog/angular-reactive-form-custom-validator-for-orcid/

user-edit.component.ts

...
import { isORCIDValidator } from '../../shared/index';

@Component({
    selector: 'user-edit-component',
    templateUrl: './user-edit.component.html',
    styleUrls: ['./user-edit.component.css']
})
export class UserEditComponent implements OnInit {
    
    @Input() user:User; 
        
    urlRegexPattern: string = 'https:\/\/orcid\.org\/.*';  // Regex pattern to ensure URL starts with https://orcid.org/
    // TODO Regex pattern for 16digit part following this 
    
    /* Creating form */
    userForm: FormGroup;
    // naming form controls as class properties means we can refer to them by name in the html template - see: https://codecraft.tv/courses/angular/forms/model-driven-validation/
    ...
    orcid: FormControl;
    ...

    constructor(private userService: UserService) {
        
    }
    
    createFormControls() { 
        ...
        this.orcid = new FormControl(this.user.orcid,[Validators.pattern(this.urlRegexPattern),isORCIDValidator]);
        ...
    }
    
    createForm() {
        this.userForm = new FormGroup({
            ...
            orcid: this.orcid,
            ...
        });
    }
    
    ngOnInit() {
        this.createFormControls();
        this.createForm();
    }

}