Can I update Big Sur to Venture without updating first to Catalina?

You have the operating system name order wrong. You can upgrade from Big Sur to Ventura if your Apple hardware supports the upgrade. See your Apple () menu > About This Mac. On that panel's product description line, observe what is in parenthesis, and if that hardware year agrees with macOS Ventura is compatible with these computers - Apple Support, then you can upgrade from Big Sur to Ventura. One clue to this is if System Preferences > Software Update on Big Sur shows an entry for a Ventura 13.4.1 (or later) upgrade.

Before you do any upgrade, check that your printer/scanner/multi-vendor provides drivers for Big Sur, or your device if networked, is supported by Apple's built-in AirPrint, which requires no vendor drivers. You may want to also confirm that your third-party applications also have versions that the vendors' indicate Ventura compatibility.

You also should perform a last Time Machine backup before any operating system upgrade, and set that external drive aside, not using it for the first Time Machine backup after the upgrade. For that, you will need a new Time Machine backup drive that is 2.5 - 3x the size of your internal iMac drive capacity and formatted as APFS using Disk Utility.

I think what you mean is upgrade to Monterey first. Catalina is older than Big Sur. Yes, you can upgrade directly to Ventura if your Mac is compatible.