How to Display children on the Taxonomy term page?
I finally found the solution. My Drupal is in french, I tried to translate, but my translation may not match the exact words :)

Go to View and edit the default Taxonomy term (content) page.
In Contextual filters :


select "possède l’identifiant de terme de taxonomie (avec profondeur)" and configure like this :


depth : choose the depth you want
check Allow multiples values
check Provide a default value and choose Taxonomy term (ID) from URL
select Filter by elements that share all terms
check Override title and write {{arguments.tid}} in the field
check Specify selection criterion and choose Taxonomy term (ID)

select "possède l’identifiant de terme de taxonomie avec modification de profondeur"


Now, if you have a complex taxonomies, go on a taxonomy term page may display the same result several times. To prevent this, in your View, go to Other section (under Contextual filters) and click on Query parameters. Then check Distinct.

Enjoy !