The Preferences dialog in IDE 2.0.0 does not contain the same link.
Arduino IDE 2.x has a completely separate settings store and system from Arduino IDE 1.x. It does not use preferences.txt in any way.
Does anyone know where/how to specify/modify "build.path" for IDE 2.0.0?
I'm not aware or any way to set this short of modifying the Arduino IDE source code.
I can suggest a couple of alternatives:
You can use Sketch > Export Compiled Binary to save the binaries to the build subfolder of the sketch folder.
You can use Arduino CLI directly from the command line or a script, specifying your custom build path via the --build-path flag:
https://arduino.github.io/arduino-cli/latest/commands/arduino-cli_compile/#options
Even though it probably won't be of use for this specific goal of setting the build path, I'll share the information about the Arduino IDE 2.x advanced settings:
Two types of advanced settings are used by Arduino IDE:
Application settings
The advanced application preferences can be modified via a convenient GUI interface in the IDE:
https://github.com/arduino/arduino-ide/blob/main/docs/advanced-usage.md#advanced-settings
Arduino CLI configuration
Some of the settings controlled via the primary Arduino IDE "Preferences" dialog and advanced settings such as "Sketchbook location" and "Additional Boards Manager URLs" are actually Arduino CLI configurations. However, there are some additional Arduino CLI configuration options that can only set via the Arduino CLI configuration file.
When used by Arduino IDE, Arduino CLI uses a configuration file stored in the Arduino IDE's configuration folder, which is a different location than the default when you are using Arduino CLI directly from the command line:
Windows:
Code:
C:\Users\<username>\.arduinoIDE\arduino-cli.yaml
Linux:
Code:
~/.arduinoIDE/arduino-cli.yaml
macOS:
Code:
~/.arduinoIDE/arduino-cli.yaml
The documentation for the Arduino CLI configuration file is here:
https://arduino.github.io/arduino-cli/latest/configuration/