Here are some practical examples of photos shot throughout the Sony a6400's ISO range from ISO 100 through ISO 102400.
Sony A6400 Ultimate Review
Hands-on with the Sony a6400: Digital Photography Review
Sony A6400 Review
Sony Alpha a6400 Mirrorless Digital Camera with 16-50mm Lens + 2 Pack SanDisk 128GB Card + Backpack + ZeeTech Accessory Bundle
Sony A6400 with 16-50mm Lens Review
The Sony a6400 is a Low-Light Beast on a Budget
Sony a6400 (Sony Alpha a6400) ISO Range Tests with Sample Images
Sony Alpha A6400 review - Amateur Photographer
Sony a6400 review: Digital Photography Review
Sony A6400 Review
Sony Alpha A6400 First Impressions Sample Photos
Sony A6400 Review: Updated with Pro Videographer Comments - Camera Jabber
Sony Alpha A6400 Mirrorless Digital Camera with 16-50mm Lens - GP Pro