Can't bind to 'ngTemplateOutletContext'
As per the docs:
ngTemplateOutletContext
bound toNgTemplateOutlet.ngTemplateOutletContext
So you would be able to attach context in the following way:
<ng-container
[ngTemplateOutlet]="recursiveList"
[ngTemplateOutletContext]="{ $implicit: item.childrens }"></ng-container>
Or:
<ng-container *ngTemplateOutlet="recursiveList; context: { $implicit: item.childrens }"></ng-container>
Angular needs to know what view you intend on adding your context object to, so ngTemplateOutletContext
won't work on its own AFAIK.
Source, Demo