Great question!
First start where Michael directed you. You'll need an Apple Business Manager (ABM) account.
Next, you'll need to start looking into Mobile Device Management (MDM) platforms. There are literally hundreds to choose from. I personally use Jamf Pro in my org, but I've also used Mosyle, Jamf Now, Fleetsmith, and Meraki. Once you decide on the platform that works best for your needs and budget, you'll need to get all your devices enrolled. Your MDM platform will have training specific to them for this. Your MDM platform will also have training on how to manage the devices.
You'll also need an Apple Push Notification Service (APNS) certificate. This is free. The number one thing to know here is to use a central account, not one associated with a single individual (if that individual ever leaves for whatever reason, you'll be glad you went with a central account).
I also suggest looking at the World Wide Developer Conference (WWDC) presentations from the past several years on device management. You can also look at the Apple documentation on the MDM protocols. I've pasted a bunch of them below.
MDM overview for Apple devices
MDM Settings for IT Administrators
Device Management | Apple Developer Documentation
Mobile device management security overview
Managing Devices and Corporate Data on iOS
Get started using Apple Business Manager
Common mobile device management settings
www.jamf.com
www.mosyle.com
www.fleetsmith.com
www.meraki.com
www.kandji.io
