Hi there @OliviaMichaelCo .
Using an unpublished theme sounds perfect for your needs. You can change store layout, colours, images, videos and over all aesthetics without ever “publishing” the theme. As long as the theme is not published, then it will not be visible to your customers. You can have up to 20 unpublished themes at once for your store, which allows you to play around with different looks without changing the actual published store.
I have a guide here on how to use themes within your store, I hope this helps. I’d love to help you out with some business growth ideas - how do you feel things are going at the minute? Is there anything you’d like to improve or change?