...I'm traveling to Paris in July and in order to save room in my luggage (and to make sure my clothes stay clean), I planned on buying toiletries like toothpaste, shampoo, conditioner, etc., after arriving. Is there an equivalent of a Walgreens or Target in Paris (specifically the 6th district) where I can do this?

"The guy who suggested Monoprix is right. You can also look for pharmacies (look for the green cross)-- they also sell toothpaste, sunscreen, shampoo, etc. If you can bring your own toiletries, you can save some money bc the toiletries in France are more expensive than in the US. Also, for some reason, it's easier to find Colgate toothpaste there than Crest. You can use zip lock bags to store your toiletries so there will be less chance of spillage."
(chosen answer)