How can I put calendar and reminders back on my MacBook even if I use I cloud?

Do you have Calendars and Reminders syncing turned on in System Preferences/iCloud (Apple ID for Catalina or later)? That shout sync the data to the Mac.

If necessary, try going to System Preferences/iCloud (Apple ID for Catalina or later) and stop syncing by unchecking the box. Wait a couple of minutes, then check syncing. Allow time for the sync to complete. The photos sync is extremely slow. It could take several days or more for the photos to sync..

Last resort  - have you tried signing out of iCloud, restarting, and then sign back in?

See the Apple Support article below. 

Contacts, Calendars, or Reminders - Get help using iCloud.     

Not sure what you mean. Calendar and Reminders are on your Mac as apps.