[NAME] -  Do you only have Intel UHD 630 Graphics, and no add-in video card? What app(s) are you running when this happens? Can you test this monitor on a different PC or a different monitor on this PC, using the same video port (eg VGA) and cable? What CPU do you have in the Inspiron 3880 and how much RAM is installed? Did you look at the Win 10 Power & Sleep options to make sure it isn't set to turn the monitor off after X min?  
I just bought an Inspiron 3880. It has Intel UHD Graphics 630. I am not gaming, just basic internet use and store/view photos.  My monitor is 10+ years old - Acer AL2216W recommended resolution something like 1500 x 1050.  I use Dell Support Assist and drivers are up to date as of today 3/28/2021.  When I first started the PC, I got a screen blackout briefly, and I was like "oh great--a lemon".  Since all the drivers are updated now, it works fine for awhile, but unpredictably, the screen will go black. The hard drove churns, and the screen might return every 10 minutes to accept a next operation, but it will go away again.  I basically need to hard-power down.  I have reduced Display resolution, and it still can lock up.  Lately, it is locking up more I notice at Windows Update???   I do not have extended support from Dell. I am no power user for sure--basic use.  Is it likely my aged monitor is an issue and I should just replace with a new (and assured compatible) Dell monitor?  Or do I need to pay/upgrade support to troubleshoot because it is something in the video adaptor, Smartbyte, or other?  To me, this Dell 3880 should work out of the box, right?!   Can someone advise my next steps.      
Inspiron 3880 w/ old Acer Monitor - Screen Goes Black