MSI enables Resizable BAR support on its RTX 30 series GPUs using MSI Dragon Center and Live Update | OC3D News (overclock3d.net)
 
MSI has today updated its Dragon Center and live Update apps to deliver Resizable BAR BIOS updates to the company's RTX 30 series graphics card, giving owners of their graphics cards a simplified BIOS update process. This functionality will allow owners of MSI's RTX 3060 Ti, RTX 3070, RTX 3080 and RTX 3090 graphics cards to gain support for Resizable BAR when their graphics card is used with compatible CPUs and motherboards. This process can deliver a considerable performance boost in supported games. 

Thanks to MSI's updated Dragon Center and Live Update apps, MSI RTX 30 series GPU users can update their graphics card's BIOS with little room for mistakes. This makes the BIOS update easier, less stressful and safer than more traditional GPU BIOS updating methods. To download the latest version of MSI's Dragon Center and Live Update software, please head over to your graphics card's official webpage, navigate to its "support" section, and find MSI's official download links under the page's "Utility" tab.  
 
Looks like MSI is trying to make BAR support as easy as possible for its customers in my opinion.