React native has had quite some improvements and changes
but a lot of issues I've had involve getting it to work on
my M1 macbook, here's a few things to do.

If you can't get it to find -lDoubleConversion
You probably messed the Podfile.lock,
remove the file and the Pods folder. Then try to re-install
pods using pod install and see if it builds.

If not,
then remove the contents of DerivedData, which can be done like
so on any mac unless you changed it location.

rm -rf ~/Library/Developer/Xcode/DerivedData/*

If there's a build issue and you are missing a module map
If it's a package from the react-native library then you should just start a new react-native project on the side, copy it's Podfile and
then run pod install with that to see if it fixes it.

If it's a additional library or package you installed later, then you
should delete the yarn.lock file and try to pin down the version of
the package, remove node_modules and install both the node and ios packages.

rm -rf node_modules
rm -rf ios/Pods
cd ios; pod install; cd ..