check if select statement is true in a function in pl/sql

Question

so i have a table called cars designed like this: ID, Model, Category, Availability. The categories are standard and luxury. im trying to write a function that returns either a boolean or an int like this :

function(id)
if category == luxury;
return 1;
else return 0;

i did this select statement but i dont know if i can use it

SELECT (CASE WHEN Category = 'Luxury' THEN 1 ELSE 0 END) AS is_equal
FROM CARS
WHERE ID = 'TM63DTI';

I have to do it in pl/sql. its for a school project and im stuck at this point. I dont have an error with this select statement, i just dont really know how to use it. Maybe suggest an idea of how i can approach this.