Restoring Backup to new iMac using USB Drive

You would not do a restore.

Instead, you would plug your Time Machine backup drive into the new Mac, and tell Migration Assistant to migrate from that Time Machine backup. Migration Assistant would copy over your data, but not the old operating system; when you were done, the new iMac would still be running Sequoia.

Transfer to a new Mac with Migration Assistant - Apple Support

Notes:

• You will need to handle the USB-A (2009 iMac) vs. USB-C (2024 iMac) difference in some way. There are many ways of doing so, including plugging your old drive into an Apple USB-C to USB Adapter .
• If you are using 32-bit applications on the old Mac, they won't work on the new one.
• If you are using 64-bit applications on the old Mac, Rosetta 2 might let you run some of those on the new Mac. Chances are that even a lot of your 64-bit applications will break; going from El Capitan to Sequoia would be a jump of nine major OS versions, even without the change from an Intel chip to an Apple Silicon chip.

You'll be able to plug it in with an USB to USB-C adapter and migrate from the backup, but not restore it.

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