Look at the back of the device.
Find the ID number spelled by only 4 letters and numbers. (e.g.ID:N6H7)

Search by ID number
Download the latest firmware package
Follow the instructions in the firmware package to update your device.

Please check the following tutorials of software upgrade instructions:
Get MTK_Upgrade Tutorial: MTK Upgrade Tutorial (Android 13)
Get RK_Upgrade Tutorial: RK Upgrade Tutorial
Get Unisoc_Upgrade Tutorial: Unisoc Upgrade Tutorial