One of the Oracle 23c extensions that is not in the spotlight is the possibility to pass more than 2 parameters to the concat function. In previous versions of Oracle concat was limited to 2 parameters.

Syntax diagram up to version 21c:

now with 23c the diagram looks like this:

I have tried to call concat with 129, 257 and even 1001 parameters. Too me it looks like the number of parameters are only limited by the possible size of the resulting datatype.

select concat('A','B','C') as resulting_string

RESULTING_STRING
----------------
ABC