one database, multiple demo sites, same content, additional wp_options tables

I found these instructions:
https://wordpress.stackexchange.com/questions/173127/two-wordpress-sites-two-themes-one-database-same-content?newreg=51a9c01048c74fae84db3b5aaedb6643

for accomplishing this, but when going to apply, the wp-settings.php file in my version of WP, the listed lines of code are not listed…

I’m new to this concept of using the same DB, so please let me know if I’m missing something obvious… Do I just add all the code included in the above post to the wp-settings.php file and alter the appropriate lines as suggested?

Thanks in advance for your help!
Derek