can I still get apples support for my 12 Pro Max purchased in 2021

The regular 1 year (2 years in some countries) warranty cannot be extended once it expires.

If you purchased Apple Care+ within 60 days of having purchased the iPhone, it can be extended once it expires.

click here ➜ Extend your AppleCare+ coverage - Apple Support

With that said, without warranty or Apple Care+, Apple will still repair your device if required, but you would need to pay for the repair.

You should have received an offer to extend your warranty after expiration for a monthly fee. You have thirty days to accept that offer. You may be able to still purchase AppleCare after that but would likely require you bring the iPhone 12 Pro Max in for inspection and diagnostics before approval.

As for software support Apple recently announced it would support its products for a minimum of four years with updates and security patches.