You can do routine driver updates safely using Dell Update because those are easily undone. But, why put extra layers of software (eg, Dell Update) on top of Windows, in between a BIOS update and your PC?  IMO, that just increases the risk of a failure which might permanently brick the motherboard. But in the event of a failed BIOS update, you can try the methods detailed here to attempt a BIOS recovery. To run the update via the F12 menu, download the BIOS update .exe onto an empty (non-bootable) USB stick using any Windows PC.  Plug that USB into the XPS 8940 with the power off.  Then power on and start tapping F12 when you see the Dell splash screen. When the F12 boot menu opens, select the option to flash update BIOS and follow the prompts. Then sit back and let it run. The PC will reboot itself at least once during the process, and may look like it completely shut itself off and doesn't do anything for ~5 sec. Just leave it alone!  Don't press any keys, don't click the mouse or power PC off. Just wait until you're safely back at the desktop. I never let Dell Update or SupportAssist manage BIOS updates on my XPS 8930. I don't even do them manually inside Win 10. I only ever use the F12 boot option...
Has anyone installed this yet that can confirm this update doesn't cause any problems? So far this year I lost an XPS8930 Desktop to a flawed BIOS update.  That machine had a Pro Support contract so Dell replaced that with an XPS8940 Desktop.  Right off the bat the 1st BIOS update for the XPS8940 'worked' but led to the power light flashing an error code and the inability to run Diagnostics from the boot menu.  That lasted a month or so until Dell released a non-BIOS update 2 weeks ago that fixed it.  Its not so much these issues but I easily spent 60+ hours with tech support over the phone, discussing via email or on their visits to my home and for the next week or two I just don't have the time to deal with another flawed BIOS update.  So prior to installing it, I'm wondering if anyone already has and can confirm its 'good to go'.  As noted in the header, its version 2.0.12 and was released last week.  It was picked up today by Dell Update. In advance, thanks for any feedback anyone may be able to provide to me.
XPS8940 lastest BIOS update 2.0.12 current release date 21 Apr 2021