I followed

CodePudding user response：

In iOS 15, the

If you don't want to use a configuration, and instead want the pre-iOS 15 behaviour, change "Style" to "Default":

CodePudding user response：

Two things....

First comment: this is likely being caused by the new Button style. If you change it from Plain to Default:

IB should keep the size at 200 x 100.

Second comment: it's a much better idea to assign constraints exactly as you want them rather than relying on IB's "automatically fix the layout."