You can install and use one of Shopify product page builder app from https://apps.shopify.com/search?q=product+page&st_source=autocomplete
Charles here from Shogun Page Builder. :) I see that you're looking into trying out a page builder that offers product page editing capabilities. I'd like to help you choose the app that's right for you.
Most page building apps on Shopify allow you to use a free trial to test out some of their features including Shogun. On our base Build plan and up we here at Shogun have product page editing available in the form of both editing an existing page and creating a completely custom product page. Existing product pages are great if you're fairly happy with your product page or are using other third party apps such as subscriptions while custom product pages are great for creating your own unique layouts. We also have several helpful features for building out product pages including a review element that integrates with Yotpo and Shopify Product Reviews.
If you have any further questions about Shogun please feel free to reply here or to reach out directly to us.
You can use Shogun or PageFly :)
Both solutions provide the free trial, so just get started with both to fully explore what's the best one to match your needs.