Epic Threads Little & Big Boys Solid T-Shirt

Macy's

Exact color match (vibrant royal blue), Plain, solid design, Short sleeves, Crew neck, Appropriate for a child, Basic t-shirt style matches

Zara Kids Basic Heavy Weight T-Shirt

Zara USA

Very similar blue color, Plain, solid design, Short sleeves, Crew neck, Appropriate for a child

A2y Kid's Heavy Cotton Crew Neck T-shirt

Walmart - Seller

Kid's short-sleeve crew neck t-shirt, Dark blue color is a very good match, Plain design, Heavy cotton material (plausible)