Clarification on RLS policy

Hi Team,

We are presently using Postgresql:PostgreSQL 15.12 on x86_64-pc-linux-gnu,
compiled by gcc (GCC) 8.5.0 20210514 (Red Hat 8.5.0-23), 64-bit
I have a scenario where
1.I need to enforce RLS policy on a table for Select by calling a Function
2.The function would return a character varying string which should be
appended to the select as a filter.
Ex: Select * from employee would be appended with where 1=1;
3.When we try to implement it says the below error.
ERROR: invalid input syntax for type boolean: "1=1" CONTEXT: PL/pgSQL
function function name(name,name) while casting return value to function's
return type
4.It works fine on Oracle. Can you please suggest how to fix this issue?

Rg
Vydehi.