This is shockingly generic.

It also doesn't specify shades of colors involved, number of points on the stars, arrangements of stars, or size of the canton.

That being said, according to WP, it looks like the US government does use standards for colors; just doesn't expect others to do the same:

https://en.wikipedia.org/wiki/Flag_of_the_United_States#Design

I know that France recently altered the shade of blue that they use to be a darker one on their flag, so there is probably some variability in a number of countries.

https://en.wikipedia.org/wiki/Flag_of_the_United_States#Design

According to the U.S. Army Institute of Heraldry, the United States flag never becomes obsolete. Any approved American flag may continue to be used and displayed until no longer serviceable.[188]

Well, that provides for some unorthodox options.

https://en.wikipedia.org/wiki/Grand_Union_Flag

The "Grand Union Flag", or the "Continental Colours", (also known as the "Congress Flag", the "Cambridge Flag", and the "First Navy Ensign") was the first national flag of the United States of America. First hoisted on December 3, 1775 by naval officer John Paul Jones, the flag was used heavily by the Second Continental Congress of the United States, as well as by Commander George Washington in his Continental Army during the early years of the American Revolutionary War.

Similar to the current U.S. flag, the Grand Union Flag has 13 alternating red and white stripes, representative of the Thirteen Colonies. The upper inner corner, or canton, features the Union Jack, or flag of the Kingdom of Great Britain, of which the colonies were subjects.