That is not the case at least in the UK; you have 14 days after receiving an item, for any online purchase you make, to return it, even if you just changed your mind.

Consumer protection regulations are genuinely so nice for feeling at ease with buying stuff online.

It is not the case in the EU, the legal term is "cooling off period". You get 14 days to change your mind for physical products ordered online

In Brazil you have 7 days to return any online order, no questions asked. You can use the product and return if you don’t like it, provided the product is not scratched etc. Companies might try to bullshit you and say that the ToS states that they only accept returns for products that weren’t opened, but they always cave after I send them the exact part of the consumer laws that support me. They have to refund the full amount, including shipping.