Does Iowa State have a weed-out process like Wisconsin (college GPA to stay in an engineering major may be as high as 3.5, depending on major) or a competitive secondary admission process to declare an engineering major like many other state flagships? It does not look like either is present at Iowa State from its web site.
However, a high school B student may be more likely to find that college (perhaps even more so for engineering) is “hard” or seems like a “weed-out” environment than a high school A student.