How can I update macOS 13.0 to 13.6.4 without updating to Sonoma

Check the Software Update section in System Settings.

Below the update to Sonoma, should be a section titled something like "Other Updates Available".

Check in there for any other Ventura updates that may be available.

Try from here -

How to download and install macOS - Apple Support

Good luck; the App Store method offered me 13.6.4 when I checked a little while ago.

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srb