Drupal 8/9 add a new region to the child template

In some situations, we may get a unique design for different pages so that there may be a chance to override the main region. So here is a solution for this, we have a parent as the main region in page.html.twig and banner is the sub region that is related to the main parent region and we can use this page--front.html.twig by extending the main region twig.Use Extending Twig Templates of block to add a new region to the child twig template.

Note:If you haven't created child template, then you should create a page--front.html.twig template.