If you enable the maximum energy savings settings, you should be able to keep loss to 1-3 miles of range per day.
However, that's assuming you are under cover and not exposing the car to high or low temperatures requiring the climate system to engage to manage the battery pack or interior temperatures.
With a 2018, you should have MCU2, so the maximum energy saving settings would be: range mode (on - not sure if this helps while parked), overheat protection (off), smart preconditioning (off), climate system (off). MCU1 vehicles also have energy savings settings on the display settings screen (enable the energy savings, turn off always connected).
You should be OK with a 2018 S P100D for 5 days, even if you park outside in colder temperatures (others are reporting 15 miles of lost range per day).
Though if you're concerned, try doing a test and leave your car parked outside, unplugged, overnight in the colder temperatures and measure how much loss you're seeing per hour - and then use that to extrapolate to your extended outside parking. Since changes can be introduced in software updates, before we plan to park for an extended period, I usually do a test just to confirm we shouldn't have a problem.
And, if you can park under cover, that can help...
