Drupal 8.x

How to write the custom Drush Commands in Drupal 8?

I have overwritten my node page as per a special layout. A main block content and a left side content.
This format was to display Content type ARTICLE.
But now that i created a new content type: TEAM (Gathering the team member of the site) i want to display the team member individually.
I came to understand that every content use the page /node; So the format with a left-side view is also appearing on the individual TEAM member page.

We are changing our domain name to a new one, and I've been trying to fine documentation on how it's best done. I find lots on migrating to a new server but I can't find staying on the same server but changing the domain name. This will be an exact copy, all done on the same Plesk/Linux based server. The only change will be the domain.

Does anyone know if there are instructions/checklist on how that's best done?

Can someone tell me what the icons and buttons were made with on this site ..

Home | Front Range Fire Rescue (colorado.gov)

I have adapted the embed code to my site...

Home | Town of Dinosaur (colorado.gov)

I would like to know an easier way to do this.  I am only a programmer for the site and don't have access anything except my landing pages.

Thanks..  Jim

I have done my Drupal 9 site development on my local setup.

I tried the steps given in this page to move the site to my shared hosting.

https://websitemigrationguides.com/guide.php?migrate=6

I installed database and uploaded the data into it ... and verified it.

However when I try to invoke the site, I get this error:

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.