I just bought IPad Pro 12.9 the store it has Microsoft office. And mine don’t have. Where I will find that

You can download the apps for free by using the App Store app on your iPad. Note that they are individual apps (e.g., Word, Excel, etc rather than a single Microsoft Office). Also, you will need an Office 365 subscription to create/edit documents on any iPad larger than 10.1 inches. You can subscribe to that through the app you download but I prefer subscribing directly through Microsoft: https://products.office.com/en-us/compare-all-microsoft-office-products?&activetab=tab:primaryr1

That's hard to follow.

Do you mean the Apple Store demo model had MS Office on it, and you're wondering why the one you purchased doesn't? If so, it's because Office isn't free. You have to buy your own copy. It was on the store demo unit so customers can see more of what an iPad can do than just the Apple supplied apps.