The border settings fall under the Design Tools section for any component properties.
You can customize the border for any type of component. We will be demonstrating how to do so for a button, but the same method applies to other components as well:
Click on the component on the canvas that you would like to adjust the border for. Its corresponding properties will appear on the right.
Click on Design Tools.
Under Border, you will see a dropdown with the following options:
Select the kind of border you would like to customize for your component. In our demonstration, we have selected the Dashed border type.
Adjacent to the dropdown, you can click on the colour block to select your desired border colour.
Next, you can toggle the Weight of the border with the corresponding arrows, or enter a value in the input box.
Lastly, you can adjust the Radius or roundedness of the border, by clicking on the corresponding arrows or enter a value in the input box.