Earlier quoted context omitted.
Just make sure the model you're getting supports S3 sleep mode (AKA real sleep mode) before hand. A lot of the newer Dells don't. Its something the OEM needs to support in the BIOS, so you can't just fix it by installing a new distro.
Since at least the 2019 model Dell XPS 13s no longer have S3 sleep mode and instead uses Microsoft's "Modern Standby" (s0ix)[1], which consumes tons of power whilst in "sleep" in order to have slightly quicker wake times. [1] https://www.dell.com/community/XPS/XPS-15-9570-BIOS-1-3-0-sl...
Unless it pulled a breaking Windows update at night so the laptop won't boot anymore the next morning.