My wife's Galaxy Note5 was just updated and now the calendar dates in month view are much smaller. She is very unhappy!
The updates for phone running Android are developed by Google, so you may have better luck reaching out to their support forums with any complaints about the latest update. That said, if the smaller size is a significant problem, then a temporary work around might be enabling Screen Zoom.
Settings > Accessibility > Vision > Screen zoom
I hate the latest update to anodroid system on my note 5 as well. The all white color is horrible and hard on the eyes. The small font on everything is awful this was not a good update at all in terms of visual and user-friendly.
Yeah, this new update sucks and now my Note 5 takes 4 hours to charge. It keeps telling me to plug it into factory charger when it already is. . I guess that's one way for Verizon to get you to upgrade start messing with your older phones.
settings/accessibility....you can increase the size of the font or make bold.