Paris Left Bank vs Right Bank

Look at the river and see which way the water is flowing. If the water is flowing to your left, you are on the left bank.

I'm not quite understanding what you are asking.

If you are at the the Eiffel Tower, Musee d'Orsay or Luxembourg Gardens, then you are on the left bank.

If you are at the Arc de Triomphe, the Louvre or Sacre Coeur you are on the right bank.

Notre Dame and Sainte-Chapelle are on the Ile de la Cite. This island is in the Seine River which flows between the left and right banks.

On a map, area south of the river is the left bank, this is the oldest part of Paris. The area north of the river is the right bank.

Do you have a smart phone? Open the map feature and see if you are north or south of the river. If you happen to be on either of the two islands in the Seine, they are part of the Right Bank.

Imagine you are riding down the Seine on an inner tube. As you proceed facing the direction of the flow, everything you see on your left is the Left Bank. Everything on the right is the Right Bank.