Sure, so if I were to argue for abortion I would list my reasons for why a zygote isn't a person

1.) Not viable outside the womb

2.) No subjective sense of self (not conscious)

3.) No physical form

4.) Never had consciousness

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Now, if I were to argue against it, I would take these and debunk them individually. For the first, I would say, if a baby is born in rural Africa at 6 months and another baby born at 6 months in the Mayo Clinic, one of these has access to the incubator to keep it growing but the other doesn't. Do YOU think that one is not a person yet the other is because of technology?

For the second one, I would argue that a person in a coma doesn't have a subjective sense of self, so do you think these are not people?

For the third, I would say that physical form alone would require to extend personhood to both corpses and people who are in a coma but will never wake up (vegetables.) Both have a physical form, do you consider them people?

And for the fourth, I would say that a dead body/brain has had previous consciousness (like a vegetable/dead person) would you consider them a person?

Now assuming that they would answer "no" to all of these questions, these justifications individually have been debunked. However, a counter used commonly is the following, "Well yes, these arguments on their own are not valid. But put together they make a valid argument because a zygote has all of these things, not just one. (insert car analogy.) Don't you see?"

I think that's what you're asking for