iPhone 14 Pro Max doesnt support esim

I'm not sure how you could have an iPhone Model A2651, which has a physical Sim Slot? But even if it does, it's your carrier who provisions your account for eSim. Apple doesn't do this. Your carrier does. Elevate this higher within your carriers support. Until they send an update to your iPhone for you to use eSim, you simply won't see the option on the phone.

Who is Unitel? I'm in the US and I've never heard of them? Are you using a phone manufactured for the US market in another country?

Here is a link from Apple, listing carriers around the world who support eSim --> https://support.apple.com/en-us/101569

Unless I'm missing them, I don't see Unitel listed.

Yes, that is an iPhone manufactured for the US market. The phone does not have a physical Sim slot at all, but does support eSim as long as your carrier supports eSim and you have contacted your carrier to set up eSim on the phone.

Sorry, but we can't help you. You have to get support from your Carrier directly.