Yes. Styleworks is completely free to use.
You can create as many styles as you want and export them as Word documents or Markdown files at no cost.
To have your preferences enforced automatically across documents using PerfectIt, you need an active PerfectIt subscription. If a style is more than 50 lines, you will need a PerfectIt Elite subscription (or higher) to export it to PerfectIt. Please see Why do styles over 50 lines need PerfectIt Eliter Tier? , it's not as limiting as you might think!