Bind Widget

/* BindWidget meta means the Blueprint will not compile unless there is a child component in the UMG hierarchy that matches the exact name and type or child of type.
* Note: There is a possibility of this being nullptr if not using a blueprint class. */
UPROPERTY(EditAnywhere, BlueprintReadOnly, meta = (BindWidget))
    class UTextBlock* TXT_Tooltip = nullptr;

Note: This pointer isn’t assigned until AFTER the widget is made visible (ie, AddToViewport, AddToPlayerScreen, WidgetPointer->AddChild).