I take a lot of photos on my iPhone 17 and have 48mp HEIF enabled permanently on both the main and ultrawide cameras.
The benefits are higher resolution for cropping and the odd Photo print.
Another difference between 24mp & 48mp is that the 48mp mode produces brighter photos with less contrast.
Subtle but noticeable. Some examples below, standard photographic style with no edits.
24mp
View attachment 2626022
48mp
View attachment 2626021