I Want To Be Somebody New! is a 1986 Beginner Book written and illustrated by Robert Lopshire, and is a sequel to Put Me In the Zoo.
The story begins with Spot and two kids. They show the events of what happened when he got removed from the zoo and is now a circus animal. He decides he should do no more spot tricks and should be somebody new.
Spot transforms into an elephant. Elephants are big, but Spot doesn't think being big is fun; he's too heavy for the seesaw, he can't walk on a fence or squeeze between small spaces, his house is too small to live in, and he can't sit in his own chair.
Now, Spot transforms into a really tall giraffe, but being a giraffe is even worse; his head is too high and birds might hit him.
Now, Spot transforms into a tiny, small mouse, but being small is even harder than big or tall. Spot can't even sit in his own chair, and his house door is too big to open up. Also, he must hide inside and not make a sound and watch out for hazards such as cats and traps.
The kids still like Spot, whether he is big or tall or small, so Spot decides to be himself again.