How many strips are used for water test of iPhone 12 Mini?

I had my phone in a zip lock bag in my pocket while out on a small boat. Unfortunately, when returning to shore, I had to jump in to walk the boat the last few feet. Water reached just below my waist, so my phone, in the bag, was maybe a few inches deep for about 20 seconds.

I found out a few minutes later that the bag leaked as my phone was wet. I didn’t worry about it too much until I went to charge and the phone said there was water detected in the lightening port.

Everything else on the phone is functioning perfectly with no obvious signs of water intrusion or damage. I had planned on upgrading soon, but before I do, I would like to check the water test strips. This is an iPhone 12 Mini. How many strips are there and where are they?

thanks!

[Re-Titled by Moderator]