smbios advice 5700 xt

hello all

I currently have an i5-9600k and an rx 580 and use iMac 19.1 smbios

I have a radeon 5700 xt on the way and wondering whether I might expect better performance with iMac 19.1 or by disabling igpu and using Mac Pro or iMac Pro smbios

as always, thanks for any tips, wisdom, etc