Development tools for Zephyr on STM32Workbench for Zephyr: VS Code extension to set up, build, flash and debug Zephyr applications on STM32.Devicetree manager: browse, edit and visualize Zephyr devicetree, STM32CubeMX-like for Zephyr.
The setting is available in the dialog whan you create your custom board; the default is STlink-v2-1, but you should select the right debugging device at this time. If you make a mistake, just delete then re-create your board.