In IntelliJ IDEA, you can set the target bytecode version for your project by following these steps:
From the main menu, go to File > Project Structure (on macOS, go to IntelliJ IDEA > Preferences > Project Structure).
In the Project Structure window, click the Project tab.
In the Project Settings section, click the Project language level dropdown and select the desired bytecode version.
Click the Apply button to save the changes.
The target bytecode version determines the version of the Java language that the compiler will use to generate bytecode for your project. By default, the bytecode version is set to the version of the JDK (Java Development Kit) that you have selected for your project.
For more information on setting the target bytecode version in IntelliJ IDEA, you can refer to the IntelliJ IDEA documentation.