If you have used a macro-enabled template in the past for this, it should still be on your computer in the folder you have designated for saving custom office templates.
When you use one of the templates from Microsoft, it is stored there.
I expect that within about 30 days Microsoft will come out with 2026 calendars.
You can also find free 2026 calendars on MVP Jay Freedman's download site. (https://jay-freedman.info/)
You can find a free perpetuaal calendar maker add-in on MVP Graham Mayor's site.
No one here can change how word works.
No one who can change Word sees what is written here.
This is a user-to-user forum. You are corresponding with your fellow users. We can tell you how to better use Word as it is.
People who can change Word never see what is posted here. To get their attention, use the Feedback mechanisms. Here is more information about how to do that and what to expect.
https://answers.microsoft.com/en-us/msoffice/forum/all/giving-feedback-on-microsoft-word-or-other/8df81a9b-84aa-46ef-bf88-24fb7fec96ba
Here is a link to some of the feedback:
https://feedbackportal.microsoft.com/feedback/search/fb6d67e3-301c-ec11-b6e7-0022481f8472?q=calendar
You can comment and vote if you want. I do not expect this to change. I recommend using the items from Jay Freedman, Greg Maxey, or Graham Mayor.