Creating a Drupal Field Group Programmatically
Markie
https://mark.ie/blog/creating-a-drupal-field-group-programmatically
Overriding base field labels and descriptions of Drupal Entities without custom code
Lee Rowlands, PreviousNext, May 27, 2022
https://www.previousnext.com.au/blog/overriding-base-field-labels-and-descriptions-of-drupal-entities-without-custom-code
Series on Writing Compound Fields
The Accidental Coder, Jan 2019
Drupal 9: Using Validation Constraints To Provide Custom Field Validations
Philip Norton, Hash Bang (#!) Code, Sep 25, 2022
https://www.hashbangcode.com/article/drupal-9-using-validation-constraints-provide-custom-field-validations
Creating fields programmatically and not through field configuration
Matt Glaman, Apr 4, 2023
https://mglaman.dev/blog/creating-fields-programmatically-and-not-through-field-configuration
Get the render array
// Render an entity field using the 'full' display mode.
$build['overview'] = $node->get('field_thing_overview')->view('full');