I use Xcode version 15.4 and then open a new iOS project. I tested without using pod, the project can be built in simulator iPhone Pro 15.
Then I used $pop init to create podfile and change the target iOS version to 12.0 and added pod 'Google-Mobile-Ads-SDK' pod install --repo-update then build again,
it shows

Showing Recent Issues
Ld /Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Products/Debug-iphonesimulator/l1demotrial2.app/l1demotrial2 normal (in target ‘l1demotrial2’ from project ‘l1demotrial2’)
cd /Users/ra/Documents/iOSProject/l1demotrial2
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -Xlinker -reproducible -target arm64-apple-ios17.5-simulator -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.5.sdk -O0 -L/Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Intermediates.noindex/EagerLinkingTBDs/Debug-iphonesimulator -L/Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Products/Debug-iphonesimulator -L/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator -L/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator17.5.sdk/usr/lib/swift -F/Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Intermediates.noindex/EagerLinkingTBDs/Debug-iphonesimulator -F/Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Products/Debug-iphonesimulator -F/Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Products/Debug-iphonesimulator/Google-Mobile-Ads-SDK -F/Users/ra/Documents/iOSProject/l1demotrial2/Pods/Google-Mobile-Ads-SDK/Frameworks/GoogleMobileAdsFramework -F/Users/ra/Documents/iOSProject/l1demotrial2/Pods/GoogleUserMessagingPlatform/Frameworks/Release -F/Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Products/Debug-iphonesimulator/XCFrameworkIntermediates/Google-Mobile-Ads-SDK -F/Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Products/Debug-iphonesimulator/XCFrameworkIntermediates/GoogleUserMessagingPlatform -filelist /Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Intermediates.noindex/l1demotrial2.build/Debug-iphonesimulator/l1demotrial2.build/Objects-normal/arm64/l1demotrial2.LinkFileList -Xlinker -rpath -Xlinker @executable_path/Frameworks -dead_strip -Xlinker -object_path_lto -Xlinker /Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Intermediates.noindex/l1demotrial2.build/Debug-iphonesimulator/l1demotrial2.build/Objects-normal/arm64/l1demotrial2_lto.o -Xlinker -export_dynamic -Xlinker -no_deduplicate -Xlinker -objc_abi_version -Xlinker 2 -fobjc-link-runtime -L/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/iphonesimulator -L/usr/lib/swift -Xlinker -add_ast_path -Xlinker /Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Intermediates.noindex/l1demotrial2.build/Debug-iphonesimulator/l1demotrial2.build/Objects-normal/arm64/l1demotrial2.swiftmodule -ObjC -lsqlite3 -lz -framework AVFoundation -framework AudioToolbox -framework CFNetwork -framework CoreGraphics -framework CoreMedia -framework CoreTelephony -framework CoreVideo -framework GoogleMobileAds -framework Google_Mobile_Ads_SDK -framework JavaScriptCore -framework MediaPlayer -framework MessageUI -framework MobileCoreServices -framework Network -framework QuartzCore -framework Security -framework StoreKit -framework SystemConfiguration -framework UserMessagingPlatform -framework WebKit -weak_framework AdSupport -weak_framework JavaScriptCore -weak_framework SafariServices -weak_framework WebKit -Xlinker -sectcreate -Xlinker __TEXT -Xlinker __entitlements -Xlinker /Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Intermediates.noindex/l1demotrial2.build/Debug-iphonesimulator/l1demotrial2.build/l1demotrial2.app-Simulated.xcent -Xlinker -sectcreate -Xlinker __TEXT -Xlinker __ents_der -Xlinker /Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Intermediates.noindex/l1demotrial2.build/Debug-iphonesimulator/l1demotrial2.build/l1demotrial2.app-Simulated.xcent.der -framework Pods_l1demotrial2 -Xlinker -no_adhoc_codesign -Xlinker -dependency_info -Xlinker /Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Intermediates.noindex/l1demotrial2.build/Debug-iphonesimulator/l1demotrial2.build/Objects-normal/arm64/l1demotrial2_dependency_info.dat -o /Users/ra/Library/Developer/Xcode/DerivedData/l1demotrial2-ekrzrbacazdfzvayaurpazksqssz/Build/Products/Debug-iphonesimulator/l1demotrial2.app/l1demotrial2

ld: warning: Could not find or use auto-linked framework 'CoreAudioTypes': framework 'CoreAudioTypes' not found
Undefined symbols for architecture arm64:
“_main”, referenced from:

ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Could not find or use auto-linked framework ‘CoreAudioTypes’: framework ‘CoreAudioTypes’ not found

Undefined symbol: _main

Linker command failed with exit code 1 (use -v to see invocation)