I'll group some books I have readinto non recommended (but you should check out if interested) and highly recommended:

Non recommended:

Gigantosaurus:

Dino Dana: Dino Field Guide Volumes 1 and 2

National Geographic Super Readers: Dinosaurs:

National Geographic Super Readers: Prehistoric Mammals

Little Kids First Big Book of Dinosaurs:

Recommended:

Jurassic World: Dinosaur Field Guide:

A Field Guide to Dinosaurs:

Dinosaurs: The Most Complete Up-To Date Encyclopedia For Dinosaur Lovers Of All Ages:

PNSO Children's Encyclopedia Trilogy:

PNSO Field Guide To The Ancient World trilogy:

Prehistoric Life:

Raptor Red:

Ayo i got the little kids guide about dinosaur wtf?