It's not your daughter's fault that you brought another person into the house; she should never be punished for that fact alone. Keeping her quiet during that time is your responsibility. So make it something rewarding that she enjoys doing.
A two and a half year old can start practicing quiet time every day. That's basically what you are asking for: a time where she plays quietly, building up to periods of extended time where she can entertain herself in "quietish" activities.
It's not as simple as reminding her to use hushed tones not to wake the baby, which is perfectly appropriate. It is about self-control and freedom to use her imagination to express herself or entertain herself in a quiet manner. You will need to teach her ways to do this, then encourage her, then allow her to do her own thing. You'll need to make it fun for her, and you'll need to be consistent.
Start with shorter periods during the day and gradually build up to one long period.
You can read about quiet time online. Essentially you'll need things like books she can enjoy on her own, age appropriate puzzles, crayons (markers if she's supervised), a digital timer (so she can see when she will be allowed to make noise), duplos or other building blocks, pretend food and maybe some animals/dolls to feed, essentially anything she likes to do which isn't loud. Rotate new toys in and old toys out. You needn't spend lots of money (for instance, pom poms and cups to throw them into are available cheaply at dollar stores, or you can make felt faces where she can arrange features to suit her, mixing it up - why not three eyes? - etc.)