update Android 6.0 to Android 8.0 on my RCA Galileo Pro 2 in 1
If your wifi  chip doesn't already support dual band (2.4/5 Ghz), there is nothing you can do via software or firmware to change this - it's a function of physical hardware that was built in when the tablet was manufactured.
As far as an Android update - that is usually up to the manufacturer.  There is a menu item in settings to check for system updates.  Connect to the Internet and then select this menu item - if an update is available from RCA, then it will tell you and allow you to download and install the update.
The 2020 version of the Galileo Pro comes from the factory with Android 8.1 Go edition.