Yes they will. When you get your new phone. In the Samsung Calendar, just enter your Google account under the Manage calendar section using the + symbol and you'll be good to go. As I've done in the attached screenshot.
If you just want to use Samsung solely from now on for your calendar. Then just make sure you enter your Samsung account in the field shown in the screenshot (and not your Google account) during the editing process.
Hi, I use my office 365 calendar within my Samsung calendar so that I can see my appointments at work. I just wanted to use the Samsung calender app instead of the Google calender but wanted to make sure that when I change my phone, that all my appointments and reminders will transfer over
You don't need to use the Google Calendar at all. Providing you login to the accounts you want to use, when you use the Samsung Calendar. You will see everything you've got saved in those accounts in the Samsung Calendar app, Microsoft included.