Microsoft no longer offers this via their main website for consumers, but they maintain the (community-driven, but uses Microsoft servers) or you can use the official Microsoft Software Download Center if you have a Volume Licensing account.
Microsoft never released an official Service Pack 3 (SP3) for Windows 7, meaning there are no legitimate ISO download links available from Microsoft for such a file.
Microsoft released a "Convenience Rollup" in 2016 that contains all updates from SP1 through April 2016. While not a "Service Pack" by name, it functions like one.
Best for stability. You can download original Windows 7 SP1 images and update them manually.
provide a script to install all security updates up to 2024–2026. Archive.org: Hosted mirrors of original ISOs, such as the Windows 7 ISO collection , are used by some users to find older versions. Modern Way to Update (Legacy Update)
You can manually download individual security updates and rollups directly from the official Microsoft Update Catalog . 📂 Finding a Windows 7 ISO