Ackchyually....
sure I can show my work. A few quick examples:
Oris which used to promote its large Pro Diver series and Aquis Small Seconds both of which were available in multiple colorways just years ago. In addition most of the Diver's 65 collection was available in 40 or 42.
Over the past two years all of the Diver sixty 65 releases have been smaller than 40mm. They stopped making the Pro Dover and now make one large Aquis Pro, and no longer have the small seconds in their collection. The Aquis models are mostly 41.5mm now instead of the larger sizes. Some are under that. Even the 43.5 is smaller than the older line normally. Almost every new Aquis release is 41.5 or smaller. The made one of their new in-house Aquis models with the 43.5 case all others are smaller.
Breitling has moved to make the Superocean series available in 36, and 42 whereas they used to all be 44 and 46mm. The SuperOcean Heritage which used to only be 46mm is now available in 38, 42, and 44 with only two colorways left in 46mm.
Essentially every micro brand is trying to do 38-40mm. Helm's most recent release for example. H2O which used be pride themselves on large watches haven't released a watch above 42 in years. Just a couple micro examples.
Hamilton just came out with a slew of new colorways for the Khaki Navy that are all 40 and under. Their dive line used to be all 42mm+. Now they have 4 45+ but the have 33 models between 39-44mm.
Tag released a slew of 30-40mm Aquaracers. C Ward eliminated their 43mm C60s.
That's just a few quick hits for divers only. If not just talking divers I think the move to smaller is even more so the case.
Let's not forget too that to those of use that like large watches, things like Omega going from 41mm to 42mm on the SMPc is pretty meaningless.
I acknowledge that some makers have made a few models that have gone up, but still the overall trend is to smaller and smaller watches. If you don't agree that's fine. I would prefer it wasn't the case myself anyhow... lol