I asked a very similar question a few months ago. The sleep/standby modes were behaving as other people have reported, however, the fact that the battery was draining rapidly in shutdown mode, on a new Dell with a 3 month-old battery with very few cycles, was a cause for concern. Nevertheless, I tried using the CsEnabled trick, which didn't work. Eventually, after troubleshooting BIOS features, applying the latest updates and using powercfg options -- batteryreport, sleepstudy etc.
I found a solution, which is a compromise at best. The battery drain was 20% within a few hours. But now with S3 sleep state -- it drains around 8-10% in full shutdown mode over a period of 8-10 hours. A similar drain in Standby is over a period of 15-18 hours.
https://answers.microsoft.com/en-us/windows/forum/windows_10...
https://old.reddit.com/r/Dell/comments/h0r56s/getting_back_s...