As for the standard iPhone 15 models, they could be available in pink and light blue colour options. MacRumors has shared a self-generated render of what the new colour might look like, which you can see below.

Apple iPhone 15 Pro new dark red colour
Apple usually has a tradition of releasing special colour editions for its Pro models every year. The brand introduced the new Pacific Blue colour for the iPhone 12 Pro, Sierra Blue for the iPhone 13 Pro and a new Space Black and Deep Purple for the iPhone 14 Pro. The new dark red colour option could be offered for the rumoured titanium finish iPhone 15 Pro and 15 Pro Max/Ultra.
Apple so far has released titanium Apple Watch models in a standard silver titanium colour and a darker titanium colour, but red colour anodisation would be entirely new. The 9to5Mac report says the information regarding the colour options is “still early” and things might change closer to the launch timeline. However, since Apple plans devices well in advance, the design choices should be finalised in the near future. Apple might start the engineering validation test phase of the iPhone 15 series, probably sometime in March.
Earlier, we showed you an alleged live image and CAD renders of the iPhone 15, which can be checked out here.