How do I find a receipt of what I purchased with my iPhone?

I am able to locate app purchases pretty easily using the link that you came here from..

See your purchase history for the App Store, iTunes Store, and more - Apple Support

In the section Find information about older purchases

You'll see that it instructs you to go to Settings > [your name] > Media & Purchases > View Account > Purchase History..

at the top it says Date Range and likely pre-populates with Last 90 Days.. tap that and a menu will pop up with available years..

tap 2019, then either tap All or tap on November..

Should be simple at that? When you find the app, tap on the Total Billed and it'll show you a digital receipt. Looks like it has a 'Resend' selection at the bottom as well. That might email you a copy?