Questions about default packaging size and shipping rates?

We are new to Shopify, having moved our store over from other sites. We are starting to regret moving over. Seeing that this has been an unresolved question since 2020 is simply shocking. The only answers we see come from Shopify Partners to buy the Boxify app. Sure that does not seem like a big deal, but when you have to buy this app, and that app, and the other app, and this package, that adds up for a small business. We are really disappointed with Shopify and regret the mistake of moving to it.