First, create a Posts Query with Query Builder
Select your post type and post status in General Tab
In Tax Query tab select your taxonomy and macros Current Terms
Compare operator - In
And then select this query in Listing grid
But if you need to display posts from the same child terms only, instead of this setting:
you need to create also SQL Query
And then you can use macros Query Results instead of Current Terms to include result from SQL query in your Posts Query
