Facebook Design — Devices
Facebook has great mockup templates for any design purposes.
There are a lot of services/solutions to creating mock-up and a quick Google search for "iPhone Mockups" produce about 50,800,000 results. Yikes! How can one find good quality Mockups to use in Photoshop, Sketch or Affinity Photo?
Facebook!
Facebook? Yes, that Facebook. They have a developer area where you can download all sorts of device design ideas which you can download and use as mockups.
Website description
Facebook supports a diverse audience around the world and an equally diverse set of devices. To emphasize that in our design mocks, we redrew a range of devices to show the global diversity of the people using our products. Each device comes with a bitmap of the device (with and without shadows) and the original Sketch file for that device.
We've incorporated many of these devices into Origami and worked with the Framer Team to add them to Framer as well.
While Facebook has redrawn and shares these assets for the benefit of the design community, Facebook does not own any of the underlying product or user interface designs. Please do not repackage and redistribute these as your own.
https://facebook.design/devices
Sample Design
Using the iPhone XS Max, and Dell XPS design I created the sample layout in Affinity Designer: