My unlocked Motorola Razr plus 2023 is missing "SIM Cards" option under "Network & Internet"

Have you done an IMEI check?  

https://www.att.com/buy/byod/identify?devicetype=phone

If it does indicate it is compatible it will also give you information on how to order physical or QR cards

If you are intending to use AT&T prepaid they have to send you a QR card or you can pick one up at an AT&T store.

I tried. But it still doesn't do anything.

That answer makes me think you did not do an IMEI check. When you do an IMEI check it either offers to send you a SIM card (then sends you through to order a QR card) or it tells you your device is not compatible.

AT&T may not be able to provide a download for a SIM card. And does not provide a download for a SIM card if you are looking to add AT&T prepaid service.

AT&T prepaid customers must have a SIM or a QR card mailed to them

Sorry for the confusion. I did dial *#06# and it has two IMEI numbers listed.

when I follow your instructions, there is only SIM card option available. Does it mean this phone only have SIM support? Which is not true, since the official website states this phone supports both eSIM and SIM. Can AT&T cut the eSIM feature on purpose? 

FYI, I am also in the process of asking help from official Motorola support. 

thanks! 

If you have provided an IMEI for the physical SIM slot, yes it would offer to mail you a physical sim.

If you offer the IMEI for the eSim slot, which may be identified as MEID, It may offer to mail you a QR card for esim

and yes ATT can block a esim from showing up in android.  Don't know why the would but they could.  Moto is turned into the LG of smartphones.

I'm not sure the razer + is allowed

? 

@GLIMMERMAN76 Then your answer explains everything.

@formerlyknownas It has esim. Check this:

Source: Official website

Yes we understand it is eSIM capable. That does not mean you can download an eSIM onto that phone.

And if you're choosing prepaid service you absolutely must get a QR card to use the eSIM