Create taxonomy terms
As always there is more than one way of doing things in Drupal.
I'll guess that one of the popular ways of solving this problem currently is with the Inline Entity Form module.
Once you have it installed you can go to the &quot;Manage form display&quot; of your Content type and choose the Inline entity form Simple or Complex for your Taxonomy ER field (Complex allows you to also add existing entities, not only create new ones on the fly). Adjust the settings to your needs.