Can I convert a normal video to time-lapse?

I took a video of me drawing a piece that took a very long time to make. When I finally finished and checked my iPhone, it was a normal video. How can I convert it to a time-lapse?

I've tried doing it on iMovie but it's still not time-lapse, but just quickened a bit…

You need to remove sections of the video, rather than just speeding up the entire footage. For example for a 1:60 compression ratio (ie. A minute of video, represents an hour in real life) retain one second from every minute of footage.

Yes, you can do what you want, but we don't know the duration of the original video and how much you want it to be as an end product.

For example, I to 8 hours of video driving from southern California to Northern California and using a computer based video editor (an older version of iMovie on my Mac), sped it up, rendered, imported to the video; sped it up, rendered, imported that video and sped it up and rendered - and it is now about 8 minutes. Using Final Cut Pro, I could do the same thing but probably only speed it up once to about 900% - then render.

A smartphone is not designed to do advanced video editing - the CPU is just not robust enough to do what you want.