Jamie here from Shopify. If you are using USPS to ship your products our Order Status Page (Formerly the Thank You Page) has some great info for your customers. This Shopify Doc has some great info on this. You can also look too applications like Order Lookup App and Aftership which can be used for this purpose as well.
I hope that helps!
Hello @Valentin_Gamerm ,
You can use the Shopify Shipment tracking and notify app. The app lets you create your own tracking page within your Shopify store. Since it is an integrated app, your customers can check the tracking details from within your store by using the order number and email address.