I have been playing with an app on my iPhone called slow shutter cam. It’s what I used to create the tail light trails in the trails image.
Here’s a little about the app.

The camera screen [img.1] is simple and uncluttered. While 2 buttons, a menu and a settings gear provide all the available adjustments

There are 3 preset exposures a motion blur, a light trail, and a low light mode. Each has a use. The low light mode is great for long open shutter situations like star trails or pitch black night. Light trails is more for medium long exposures like the car taillights image below. The motion blur mode can be the most interesting adding action to otherwise static images. Try it out, at only like $2 I found it worth it.