Launchers (at least Nova) do not change icons in the setting menu
then that you do not like the icons in the settings it does not mean that they do not like everyone!
accordingly, company representatives Blackview can not fulfill your request because these icons are an integral part of the shell of a specific model!
Many brand companies use their branded graphics shell in android and there is nothing terrible in this
I could do a patch that will replace the icons in the settings for the standard ones or those that you provide, but it all depends on how much you need it !?
if this is what you really need, if you have TWRP on your phone, then contact me on the website xda or 4pda and I'll try to help you
I ask you to excuse me, I do not know English, and the online translator does not translate everything correctly