In Neo4j server, APOC optionally allows you to run cypher commands after database initialization is finished. This can be used to set some dynamic settings or run some database operations.
 

apoc.initializer.<database_name>.<identifier> = <some cypher string>

We can set some dynamic settings using this method and create an user at the same time.
For example:

We want to enable parallel runtime support when the database starts and we also want to create an user "dummy" and set its password. We can add the following settings in conf/apoc.conf:

apoc.initializer.system.0=create user dummy set password 'abcd1234'
apoc.initializer.system.1=call dbms.setConfigValue('internal.cypher.parallel_runtime_support','ALL')

Once the Neo4j server has started, we would see the following logs in debug.log

2023-11-20 09:33:18.829+0000 INFO  [o.n.c.Config] internal.cypher.parallel_runtime_support changed to ALL, by dbms.setConfigValue
2023-11-20 09:33:18.839+0000 INFO  [a.c.CypherInitializer] [system/00000000] successfully initialized: CALL dbms.setConfigValue("internal.cypher.parallel_runtime_support", "ALL")
2023-11-20 09:33:19.263+0000 INFO  [a.c.CypherInitializer] [system/00000000] successfully initialized: CREATE USER dummy SET PASSWORD '******' CHANGE REQUIRED

 Another example is that we want to

apoc.initializer.neo4j.0=create index person_index for (p:Person) on (p.name) 
apoc.initializer.neo4j.1=create (:Person{name:'foo'}) 
apoc.initializer.neo4j.2=create (:Person{name:'bar'})

• https://neo4j.com/docs/apoc/current/operational/init-script/

• https://neo4j.com/docs/apoc/current/config/