How can I maximize ASUS rog zephyrus g14 battery life when I got a new pack?

You can try doing any of the following suggestions:

•  Use the function keys to adjust the display brightness.
•  If you are not using any Wi-Fi connection, switch your system into Airplane mode.
•  Disconnect unused USB devices.
• Close unused applications, especially those that take up too much system memory

ASUS rog zephyrus g14 battery

Brand new asus rog zephyrus g14 ga401 15.4V 4940mAh laptop batteries

    Price: 160 NZD
    Voltage: 15.4V
    Capacity: 4940mAh (76Wh)
    Battery cells: 4-cell
    Chemical: Li-Polymer
    Battery Color: black
    Condition: new original battery
    Warranty: 9 months
    Free shipping: 9 months
    Shipping time: 7-15 business days

You can have more information about the battery here: https://www.storebattery.co.nz/asus-rog-zephyrus-g14-ga401-15.4v-4940mah-laptop-battery-store-for-new-zealand-p-403397.html.