The permanent solution for this kind of problems is to learn Liquid, so that you can fix everything on your own. It's a fairly simple language if you have a coding background.
Ash here from the Shopify team.
I took a look at the link you shared, and I'm not seeing a large gap currently between the product photo and gallery. Here is a screenshot of how your product page looks for me:
Are you seeing something different on your end? If so, please send me a screenshot so I can compare the two and get a better idea of the issue you're facing. If you were able to resolve the issue on your end, please also reply and let me know what the issue was and how you fixed it. This could potentially help future merchants with similar issues.
As @Wahab_Ahmad and @TungDao mentioned, learning code can definitely help with identifying and fixing theme-related issues, but it can be a big commitment to learn when starting from scratch. If you're using a Shopify made free theme, our theme support team may be able to assist with theme issues that arise. For third-party themes, you can always reach out to the theme's developer, or hire a Shopify Expert for assistance.
I look forward to hearing back!