A.H.
My son was a little over two when his brother was born a couple of years ago. He still takes pride in reading his big brother books. I think a big brother shirt and a big brother book would be fine. The shirt is something that he can wear to show off his new title. You can also put a note into the book so it becomes a keepsake. There are a lot of big brother books out there. My son received a few of them but the one that stuck out the most was written by Joanna Cole and is titled "I'm A Big Brother." It is smaller so it fits smaller hands and can go on trips. It talks about a new baby in the house, how much mommy and daddy still loves you, and gives tips at the end for parents to help children adjust to a new sibling.
Congratulations and good luck!
A.
SAHM of two boys - 4 1/2 yo and a 27 month old