How do I test my large web app

I have a completed restaurant finder web application and would like to deploy it soon. I thought it would be a good idea to test it a while before I do that. But the application is already quite big and testing everything seems like an overwhelming task. I'm a beginner web developer, and I'd like to get the application to a place where it might impress recruiters. But I'd also like to get it done in a reasonable amount of time.

From a non-technical standpoint, what should I be looking at? These are the features that the application has:

-User creates an account with typical Laravel authentication

-Profile, they can change their name, bio, billing address, shipping address, and avatar. Theres also pages for their reviews, orders, favorites, feed, and cart.

-Landing page for the website is the store page, many different restaurants are listed, the user clicks a restaurant, and clicks a dish for that restaurant and they can add it to their cart. Other features include favoriting, and placing reviews.

-Viewing the public profile of other users, users can follow other users

-There is a page for placing orders, where they can place the order or also change their shipping or billing address. Then, the order goes to my sandbox Stripe account. An email is also sent to the user's email.

-I'm currently using a sandbox Mailgun for all emails, as I need a live domain to stop using sandbox mode (that's also on my to-do list once I deploy)

-It is a multi-vendor marketplace and for each order, an invoice is sent to each vendor so they can fulfill each item that they need to fulfill.

-Admin role, essentially the restaurant owners. They have a back-end admin panel which has many different features.

-Also a super admin role, they are able to manage everything on the website, like deleting restaurants, admins, or users.

-Users, admins, and super admins are their own separate guards.

Actually, I have some tests that I already wrote, and they work fine. I have tests on most pages to make sure the page loads properly, and it can not be accessed by types of users that should not be authorised.

I also have several automated Dusk browser tests:

-Users, admins and super admins can log in correctly

-User can update their billing and shipping address

-New users can register correctly

-Users can add an item to their cart

-Users can favorite a restaurant

-Users can follow another user

-Users can place an order

-Users can post a review

My biggest worry at the moment is what might happen if I seed the database with a large amount of data as I didn't really test the pagination.