How do you personally find the value a company that recently IPO’d? What do you look for?

I was looking into starting a position in Portillo’s, which is a Midwest-based restaurant chain that serves Chicago-style food. I hear a lot of people mention that it’s hard to find the true value of a company that recently IPO’d so I wasn’t sure how you guys go about it. The current price is $18.30. The more naive me would’ve thought “that’s a cheap price as is” and would’ve bought some. But I’ve learned a bit since I started investing and don’t want to be that ignorant with that mindset. I looked at them when they were over $23 a share and they’ve since dropped $5, and I’m wondering how much more they could fall. So what do you guys look for when trying to do DD on a newer company?