Setting up a view to list all items by filter Taxonomy: term *aswell as all of its children*

Any pointers on setting up a view, where the view filter is "Taxonomy: Term" -> "Is One Of" -> "something"

where i want to see "something" as well as any nodes with that are in any of the children of "something" ?

I have looked at TQL but cant see how to make this work as an argument & filter where i have the filter's exposed so a user can select different terms.

essentially i am performing a search where im trying to locate a node that falls under 3 different vocabs that have hierarchy .

For example

"search by country" AND "search by category" where i want all child nodes to be listed