Is it correct and natural to refer to a bar of soap as a "bath accessory"?
If not, what would you call it?
I'm considering a sentence like:
The hotel offers free bath accessories/bathing products.
I'd appreciate your help.
In the context you provide, it is helpful to look at Hotel websites:
Looking at some different hotel websites, bath products, bath amenities, or bath necessities are examples of options. To me any of these sound fine, but are ordered in decreasing preference
"bath accessories" suggests towel holders, soap dishes and similar items.
In British English, "complimentary toiletries" would be used.
An invigorating hotel toiletries range that includes a selection of shampoo, soap, body lotion and shower gel.
https://www.hotel-complimentary-products.co.uk/hotel-toiletries
Things like sewing kit or shoe polish might be amenities.
Cole & Lewis Deluxe Toiletries & Amenities Welcome Pack
Hotel Guest Amenities and Accessories
https://www.outofeden.co.uk/category/amenities-and-accessories