Is there a way to adjust the length of an event?
No there is not. A compromise that Wyze made in order to provide cloud storage for free is to limit the cloud clips to 12 seconds with a minimum 5 minutes between clips.
There are two things you can do:
Install a microSD card in the camera and set it to record Events Only. This will capture all 1-minute video segments with motion without limitations up to the size of the card installed (and then recycle the oldest video when the card is full).
Hop over to this post and VOTE for paid cloud storage: