is there a delay timer feature for videos

This feature does not seem to exist, but to recreate the desired effect, trimming the video may be the best option. After filming your video, open the Photos app, press your video, and press "Edit" in the top right corner. From there, press the left or right arrow and drag the slider to the point in time you want your video to start/end.

Sorry no. To my knowledge that feature is not available.

If you'd like, you can submit your request/suggestion to Apple using this link:--> Apple – Product Feedback - iPhone

Regards

Giulio