[Django]-Django.db.utils.NotSupportedError: PostgreSQL 12 or later is required (found 11.19)

You need to downgrade your Django or upgrade your PostgreSQL version. I think downgrading django will be easier. For that you can do the following:

pip uninstall django

After uninstalling, you need to reinstall django but of lower version, for that you can use the following command:

pip install django==4.1

Django 4.2 does not support PostgreSQL lower than 12(as you said that you have Django 4.2), but Django 4.1 can use PostgreSQL 11.xx. Here is the documentation:

for Django 4.2:
https://docs.djangoproject.com/en/4.2/ref/databases/#postgresql-notes

for Django 4.1:
https://docs.djangoproject.com/en/4.1/ref/databases/#postgresql-notes

ElephantSQL is currently using postgres server 11.19

psql (15.4, server 11.19 (Ubuntu 11.19-1.pgdg20.04+1)) SSL connection
(protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384, compression: off)
Type "help" for help.

You need to connect to a postgres server version 12 or higher.