Read the read on xda see below
Also want to add i tried it but it didnt work for me i had some kind of issui but was the same one when i tried it myself using fastboot so i ended up doing it a difrent way.
and below here a howto from the creator of the program.
Hello, I’m sorry to hear that you are finding Treble Toolkit hard to use. Here are some instructions:
1 - Gathering Information
1.1 - Check if your phone is compatible with Project Treble
1.2 - Check your phone’s partition scheme
Note: If your device is running Android 11 or later, then you will have the A/B scheme
2 - Gathering Files
2.1 - Download a GSI of your liking that matches your phone’s partition scheme and architecture
Note: On my experience with devices that have small system partitions, I recommend using arm builds instead of arm64.
2.2 - Download your boot.img & vendor.img (Optional)
Note: You will most likely not need this
2.3 - Update the bootloader drivers (Windows 10+)
Since an update, you will need to boot your phone in the bootloader mode, connect it to your PC, then open your PC’s settings, go to “Update & Security”, “Windows Update”, “Check For Updates”. Once you have checked for updates, select “Show Optional Updates”, check the Android Bootloader Interface one and press update.
3 - Flashing Time
3.1 - Open Treble Toolkit, select Flash GSI (Select A if your device doesn’t support the A/B partition scheme and A/B if it does)
3.2 - Select “Next”
3.3 - A new window will pop up where you can drag your GSI’s *.img file. Do that.
Note: If your GSI is not in *.img format (e.g. *.img.xz), then you need to extract it first.
3.4 - Connect your device in fastboot mode (or ADB if you have debugging enabled and have authorized the PC)
3.5 - Press “Next”
4 - Enjoy!
Note: If your device bootloops, please try other GSIs before reporting an issue, and please send feedback on your device to get a chance of participating on the Compatible Devices Program (unlock Device Specific Features on select models)