Even if you can’t draw you still can create beautiful pictures and images. Your mobile device makes it so easy to capture a picture anywhere, and most art apps have the ability to import your picture and allow you to trace over the image on a new layer. Think of it as having a printed photo and tracing paper. Depending on the app you are using the tools and layers will vary but the concept of placing your photo on the bottom layer and having a clear layer above it to trace on is the same no matter what app you use.
There are also editing apps that will turn a photo into a pencil drawing. Most art apps allow you to save the sketch in your photo album and import it into other apps for painting.
If you are unfamiliar with an app that you are using, google” how to trace an image in ____ (the name of the app you are using). The app developer and users have put lots of information & videos on line. Remember Google can be your best friend when you are looking for information.