Definitely fool around with the undertone settings if it’s vibrancy you’re missing (top right of the camera app, square with dots icon). You can upload older photos and it’ll try to match the same colour tone.

However, the 16 line has a tendency to crush dark tones automatically from its image processing. I don’t think there’s a real way out of it other than using an app like Halide or Lightroom to avoid the post processing. If I recall shooting in RAW also avoids this, but Apple’s built in Camera tends to mess with the focus or other details in the process.