Below is a full list of NLS parameters in Oracle Database, along with their default values, and scopes that each parameter is available in.

Parameter	Description	Default Value	Scope
NLS_CALENDAR	Calendar system	Gregorian	I, E, A
NLS_COMP	SQL, PL/SQL operator comparison	BINARY	I, E, A
NLS_CREDIT	Credit accounting symbol	Derived from NLS_TERRITORY	E
NLS_CURRENCY	Local currency symbol	Derived from NLS_TERRITORY	I, E, A
NLS_DATE_FORMAT	Date format	Derived from NLS_TERRITORY	I, E, A
NLS_DATE_LANGUAGE	Language for day and month names	Derived from NLS_LANGUAGE	I, E, A
NLS_DEBIT	Debit accounting symbol	Derived from NLS_TERRITORY	E
NLS_DUAL_CURRENCY	Dual currency symbol	Derived from NLS_TERRITORY	I, E, A
NLS_ISO_CURRENCY	ISO international currency symbol	Derived from NLS_TERRITORY	I, E, A
NLS_LANG	Language, territory, character set	AMERICAN_AMERICA .US7ASCII	E
NLS_LANGUAGE	Language	Derived from NLS_LANG	I, A
NLS_LENGTH_SEMANTICS	How strings are treated	BYTE	I, E, A
NLS_LIST_SEPARATOR	Character that separates items in a list	Derived from NLS_TERRITORY	E
NLS_MONETARY_CHARACTERS	Monetary symbol for dollar and cents (or their equivalents)	Derived from NLS_TERRITORY	E
NLS_NCHAR_CONV_EXCP	Reports data loss during a character type conversion	FALSE	I, A
NLS_NUMERIC_CHARACTERS	Decimal character and group separator	Derived from NLS_TERRITORY	I, E, A
NLS_SORT	Collation	Derived from NLS_LANGUAGE	I, E, A
NLS_TERRITORY	Territory	Derived from NLS_LANG	I, A
NLS_TIMESTAMP_FORMAT	Timestamp	Derived from NLS_TERRITORY	I, E, A
NLS_TIMESTAMP_TZ_FORMAT	Timestamp with time zone	Derived from NLS_TERRITORY	I, E, A

The values in the Scope column have the following meanings:

   I = Initialization Parameter File
   E = Environment Variable
   A = ALTER SESSION

In addition to the scopes listed in the above table, NLS parameters can also be explicitly set in SQL functions when you call them. However, not all functions accept NLS parameters, and so these aren’t listed in the scope column.

NLS parameters can be set in various places, such as at the database level, in an initialization parameter file, in environment variables, at the session level, and within some functions. See Methods of Setting NLS Parameters and their Priorities for a table that outlines each scope and its precedence order in relation to the other scopes.

Also see How to Check the Values of the NLS Parameters for a list of the views available for checking the values within each scope.

Table source: https://docs.oracle.com/en/database/oracle/oracle-database/21/nlspg/setting-up-globalization-support-environment.html