New sqlplus feature is introduced in Oracle 21c release sql plus for json output format, to illustrate:
SQL> show jsonprint
jsonprint NORMAL
SQL> select json(‘[{fname:”Emad”},{lname:”al-mousa”}]’) from dual;
JSON(‘[{FNAME:”EMAD”},{LNAME:”AL-MOUSA”}]’)
——————————————————————————–
[{“fname”:”Emad”},{“lname”:”al-mousa”}]
SQL> set jsonprint pretty
SQL> show jsonprint
jsonprint PRETTY
SQL> select json(‘[{fname:”Emad”},{lname:”al-mousa”}]’) from dual;
JSON(‘[{FNAME:”EMAD”},{LNAME:”AL-MOUSA”}]’)
——————————————————————————–
[
{
“fname” : “Emad”
},
{
“lname” : “al-mousa”
}
]

Related:
DBFiddle Oracle 21c: Return a resultset as JSON text—using “pretty” formatting
https://dba.stackexchange.com/questions/305548/dbfiddle-oracle-21c-return-a-resultset-as-json-text-using-pretty-formatting
See this post for information about dbfiddle:
Free online database instances (Oracle, SQL Server, DB2, more)
https://community.ibm.com/community/user/iot/communities/community-home/digestviewer/viewthread?GroupId=727&MessageKey=ca7710cd-f8d1-47bd-a774-b3e0e5d9688a&CommunityKey=3d7261ae-48f7-481d-b675-a40eb407e0fd&tab=digestviewer