Hi there,
the Codex here explains how to define your widget area:
https://codex.wordpress.org/Widgetizing_Themes
And part of that includes displaying the widget area using a function like so:
<?php dynamic_sidebar( 'home_right_1' ); ?>
In GP you can hook that function in to the available hooks ( some shown here ):
https://docs.generatepress.com/article/hooks-visual-guide/
Using a Hook Element or you can use an add_action
function.
Of course if you don’t need widgets specifically then you can just the Hook or Block Element to add your own content. And bypass creating a custom widget area altogether.