Child asylum

Hello member, hope you are all well.

I would like to ask your opinion/advice about the child asylum please. I would appreciate if any can advise. One of my friend's relative who has been sponsored and is coming to UK from Afghanistan on visit visa just before new year. He is under 18 and wanna visit his family here and want to settle here. My friend asked me that he wanna claim asylum but i had no answer to give him or advised him about the process as i have no clue about it.
I am sorry to ask these silly questions but Can he claim asylum at the airport the day he lands or what is the process please.
I was told his life is not safe there as Taliban ruling the country and are brutal.

Please advise.
Thank you.

You are going to have to be more specific.

Precisely how does the Taliban rule impact him personally?

Is he gay, from a persecuted minority (Shia, Tajik, Hazara, etc)?

The mere fact that the Taliban rule Afghanistan does not mean that all Afghans are automatically eligible for asylum.

What is his relationship with the guest family here? Are they his siblings, his cousins, his brother-in-law's sibling's second cousin once removed?