[ionic 4] How to force 'slide to left' animation on router.navigateByUrl?

Ionic Framework
1

When I click the button below, the app navigates to the child page with a “slide to the right” animation. I need to know how I can force a “slide to the left” animation when I click a button to return to the main page?

<ion-button (click)="gotopage()">Child Page</ion-button>

gotopage() {
    this.router.navigateByUrl('/childpage');
  }