Hi, and welcome to the Apple (user-to-user) Community!
Re: iPhone 16 Plus - Missing Vivid Filter
Apple support's online article for iOS 18:
Edit photos and videos on iPhone - Apple Support
says:
"Apply filter effects
On iPhone 15 models or earlier, you can apply filter effects to change the tint of a photo.
Note: On all iPhone 16 models, use Photographic Styles instead of filters to give your photos a customized look. See Change the Photographic Style of your photo on iPhone 16 models.
- Go to the Photos app
on your iPhone. - Open a photo or video, then tap
. - Tap
to apply filter effects such as Vivid or Dramatic. - To remove a filter that was applied when you took the photo, tap Original.
- Tap a filter, then drag the slider to adjust the effect.
- To compare the edited photo to the original, tap the photo.
- Tap Done to save your edits, or if you don’t like your changes, tap Cancel, then tap Discard Changes."
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As we are all Apple users, like yourself, in the community, Apple will not see your feedback posted here.
You may want to send feedback to reach those who work behind-the-scenes at Apple, and can make changes if others are also requesting them. Apple's feedback web-page: Product Feedback - Apple
All the best :-)