As per the https://developer.apple.com/documentation/bundleresources/privacy_manifest_files/describing_data_use_in_privacy_manifests Mentions that Third-party SDKs need to provide their own privacy manifest files.
What about the SDKs which are in-house? Meaning if the application contains the SDKs which are developer within the same company as the application would be treated as Third-party SDKs?
Judging by the nature of your question, I assume you're not a developer so I'll answer this as non-technical as I can. As an app developer, you are still responsible for all the code inside your app, third-party or in-house. So No, thirdparty and firstparty in-house sdks are the same in the eyes of the law.
That being said, for in-house sdks you have the advantage of choosing how you want to deal with the Privacy Manifest requirement: code dependency vs binary dependency, static linking vs dynamic linking, use whatever packaging format you want (xcframework/staticlib (.a)/.framework), etc.
If you have a ton of in-house static libraries/frameworks that you just dont want to update and they do not require being embedded inside the app bundle, you can just declare all the Private Reasons APIs Usage inside the App's privacy manifest.
Hope this helps! Cheers!