A credible leaker by the name of NewHaloLeaks has allegedly uncovered a .txt file featuring a slew of photo mode features for Halo: Infinite.
There's the option to choose a filter, use "binoculars" (likely to zoom), add a weapon scope, select borders, stickers, colors, filters, vignette, letterbox, and more. However, they added that they are not sure if there are any depth of field effects while the photo mode is exclusively available in the campaign, not multiplayer.
NewHaloLeaks has been datamining and reporting on their findings for a while now, sharing photos of the Sabre model interior, the name of the pilot from the trailers, a potential co-op mode for campaign, a custom game browser, and even a glimpse at the Hotrod - a new weapon.
You can also adjust the position in this reportedly leaked photo mode but, from the .txt file alone, it isn't clear if that references moving Master Chief or the camera.
A photo mode hasn't been confirmed by 343 Industries as of yet so it's unclear if this leak is legitimate or if it will actually be something present on launch, but it's become somewhat of an industry standard. To boot, Halo games have had photo modes before so it isn't uncharted territory for the series.
Halo 3, ODST, and Reach had a Panaromic Camera Mode that you could use for the game's theater, something that was prevalent in a lot of late 2000s, early 2010s shooters. The modern equivalent is the dedicated photo mode that saves your captures to your hardware (be it PC, PlayStation, or Xbox) rather than somewhere in-game. This would certainly continue the industry's modernizing of that old time approach.