By default, any styles you’ve applied such as a strokes, border radius or shadow sizes will stay the same when you resize a layer. If you want to scale them proportionately with your layer size, head to Layer > Transform > Scale or press ⌘K.
In the Scale Layers controls in the Inspector’s Details tab, you can choose whether your layer will resize from its center, sides or corners. Your layer will automatically scale as you change its properties.
When you’re done, simply click on your Canvas to exit scaling. Alternatively, click Finish or press ⏎.