export const routeTransition = trigger(
  'routeTransition', [
  transition('* => *', [
    query(':enter', [
      style({ 
        opacity: 0, 
        scale: 0.9 
      }),
    ], { optional: true }),
    query(':leave', [
      animate('0.2s', style({ 
          opacity: 0, 
          scale: 0.9 
      }))
    ], { optional: true }),
    query(':enter', [
      animate('0.2s', style({ 
        opacity: 1, 
        scale: 1 
      }))
    ], { optional: true })
  ])
])

    <app-nav></app-nav>
    <div 
      [@routeTransition]="data" 
      style="display: contents"
    >
        <router-outlet></router-outlet>
    </div>

Example explanation:

Triggers (trigger):
parentTrigger: Defines animations for the parent element.
childTrigger: Defines animations for the child elements.

States (state):
parentTrigger: Has the states start and end.
childTrigger: Has the states visible and hidden.

Styles (style):
Defines final and intermediate styles for different states and transitions.

Transitions (transition):
Defines how the animation should occur between states.

Animate (animate):
Defines the duration and timing function of the animations.

Keyframes (keyframes):|
Used in the transition from visible to hidden in the child elements to create detailed intermediate animations.

Group (group):
Used in the transition from start to end in parentTrigger to animate multiple properties in parallel.

Sequence (sequence):
Used in the transition from end to start in parentTrigger to animate multiple properties in sequence.

Query (query):
Used in the transition from hidden to visible in childTrigger to select and animate child elements.

Stagger (stagger):
Used with query to apply a delay between the animations of the child elements, creating a cascading effect.