I sincerely apologise for the delay in getting to your query. As a standard part of the theme the slider doesn’t have a method to alter the default width of the slider as it’s built to fit onto the default page width. You can alter the height in the theme settings though. If you want to explore further I can look into a method of increasing the width through the php code though this can be a complicated process and may potentially cause graphical glitches. Let me know if you’d like to proceed and I’ll look into it some more.