In short, no you don’t. It is your choice.
For some supports, it will be difficult for a provider to help you if they haven’t seen your plan. For example, when using a plan manager or support coordinator - they need to see what funding you have and what your goals are in order to provide their service to you properly.
For supports like cleaners and support workers, it’s not necessary for them to see your plan. The same applies for therapists like psychologists or occupational therapists.
If you would like to enter into a service agreement with a particular provider but don’t want to share your whole plan with them, you can tell them your plan start and end dates and let them know the amount of funding you have in the relevant budget or the amount you would like to allocate to them within the budget.