@Rachel433 This is an international platform so you will have guests from all over the world. In the US we provide bottom sheet, top sheet and blanket/quilt/comforter. I know that is not what is expected everywhere, so I suggest you provide what is expected in your area, but be prepared to offer additional bed linens. The problem with bottom sheet and duvet, is the perception that the duvet is not cleaned between guests.
After a while you will find out who are the guests for your place and be able to adjust to your usual guest. Hope this helps.