In Angular 2+, try the @Input decorator
It allows for some nice property binding between parent and child components.
First create a global variable in the parent to hold the object/property that will be passed to the child.
Next create a global variable in the child to hold the object/property passed from the parent.
Then in the parent html, where the child template is used, add square brackets notation with the name of the child variable, then set it equal to the name of the parent variable. Example:
<child-component-template [childVariable] = parentVariable>
</child-component-template>
Finally, where the child property is defined in the child component, add the Input decorator:
@Input()
public childVariable: any
When your parent variable is updated, it should pass the updates to the child component, which will update its html.
Also, to trigger a function in the child component, take a look at ngOnChanges.