this.router.navigate(
    [`/tickets/buy`],
    {
        queryParams: {
            event: event.id
        }
    }
)

constructor(private router: Router) {}

public navigateWithSomeState(): void {
  this.router.navigateByUrl('/tickets/buy', {
    state: что угодно
  });
}

class BuyTicketsComponent {
  constructor(router: Router) {
    console.log(router.getCurrentNavigation().extras.state);
  }
}