With our 2017 S 100D - you won't be able to upgrade to ludicrous.
Upgrades you may be able to purchase: Enhanced AutoPilot (was a $5K option), Full Self-Driving (was a $3K option), Infotainment Upgrade (replacing MCU1 with MCU2 and the console display, plus adding the Radio Upgrade to retain FM/HD/XM radio), and onboard charger upgrade (upgrading from 48A to 72A).
For EAP and FSD activation, the current prices will be different than what was available for 2017 purchases.
Our S 100D was ordered with only the 48A charger. According to Tesla, it actually has the 72A hardware already on board, and performing the upgrade may only be a software switch.
If the vehicle doesn't have the 72A hardware already, they should have the hardware available somewhere to perform the upgrade.
However... Even though we are able to charge at up to 80A at our house, we are only using 48A for our 2017 S and our 2018 X (which has the 72A charger) - since we charge overnight (when our electricity is free) and at 48A, there's plenty of time to get a full (90%) charge.
Unless you need to do a quick full charge during the day, you shouldn't need more than 48A - which is why Tesla is no longer including the 72A or 80A chargers in S/3/X/Y - and why the UMC is limited to 32A - supporting only the slower charging speeds (except for superchargers) reduces hardware costs - and doesn't impact usability of the vehicles.