Will NFC work if I have a phone case on my phone?

Yes. Providing that there is no metal or other objects such as travel or bank cards stored in or on the back of the case.

Consider that the case will also create a little distance between the phone antenna and the tag. In most normal cases this will be very minimal and have little effect. However for some of our very small tags which have a very short scan distance this may become a factor.

Using an on-metal tag at the back of the phone will allow the tags to be used if there is metal on the back of the phone and it will not interfere with the tag.
Reader - 13 Jan 2023

Those stick on bubble nfc tags that people use for contact sharing can stop the nfc working on android phones.
Reader - 01 Mar 2024