Can I activate my iPhone myself

Probably; when you set up the phone you can activate an eSIM. The way to do this depends on your carrier. If you are transferring a number from another iPhone you should be asked if you want to transfer the number from your previous phone’s SIM card to an eSIM in the new phone. If you don’t have a previous iPhone ask your carrier how to activate the eSIM in the iPhone 16. This is assuming you are in the United States. In any other country just put an activated SIM card into the new phone.

It will depend on the rules and procedures set in place by your cellular carrier. I use T-Mobile. You are supposed to be able to set it up yourself. Once it worked. Another time I had to ask them to activate.