If you don't already know who Cream is I'm gonna put her character bio from his first game in Japanese and here's Sonic Channel for safe keeping.

Sonic Heroes:

Cream the Rabbit (6 y/o)

A girl who is good friends with the Chao and always has her friend Chao “Cheese” with her. Younger than Tails, about 6 years old. She is a posh lady from a good family and was brought up like a princess, so she is very pure and honest. Strangely polite and even bows before fighting Eggman. 

She works diligently hard at everything she does and is full of curiosity and thirst for knowledge. Because of this, she sometimes loses sight of her goals and gets others into trouble, but her natural honesty and charm make her hard to hate. She speaks in a courteous language with a bit of a lisp. Her favorite food is soft serve ice cream! She can fly by flapping her big ears.

Sonic Channel:

A kind-hearted, gentle rabbit girl who is best friends with Chao and always brings her friend Chao Cheese along. She’s a hard worker who gives her all to everything, with a strong thirst for knowledge and curiosity.

She can flap her large ears to fly through the air, and her tag-team attacks with Cheese are incredibly powerful, even capable of taking down Dr. Eggman’s robots.

Influenced by her refined mother Vanilla, she speaks in a polite, formal manner. Yet she endearingly addresses even villains with honorifics like “Mr./Ms.,” showcasing childlike charm in her speech and conduct.

For a reference of the voice I want you to imitate here's a playlist with all Sonic games in Japanese. Sonic X in Japanese is also a good reference.

Solebinku's Personal Direction:

With Cream make her sound like a kid that can feel soft spoken and polite. Her whole thing is her mother raising her to be a polite Japanese girl. It is also stated she has a small lisp so adding that is important. She says things like "Amy sama" which can mean Ms. Amy again that polite idea is important. But again don't forget she's calm spoken kid but can get loud when hit the right way.

Just listen to the Japanese and you'll get what I mean. Understanding the source will make your take sound pure and proper.

Game Cutscenes:

https://youtube.com/playlist?list=PLhnIPa8XAn7x6g8UvkO0UaiTHtK-VBUbd&si=gTudY2rorUzd7vGB

General Cream voice lines.

https://youtu.be/qS8LhouZPgc?si=qDhcoDOKvJE5pLzV

https://youtu.be/pVoBS2aewrg?si=RN9dxTui9TI-dP0D

https://youtu.be/T5X9_Nkfj1s?si=0PeepBKygB1Ezz-H

If you want to learn more about the character I made a video for her on my YouTube channel:

(To be added one day...)