Honestly, I think this is a much easier question to answer these days if the price difference isn't a significant one due to the fact that the range is not that detrimental on the performance variant. If the price Delta were of significant importance to you my guess is this decision would be much easier over $20,000 as that's not an insignificant sum of money.
You may see a slightly flatter depreciation curve on the Plaid due to notoriety & scarcity for resale but when the entry point is $20,000 higher it also means that said delta will be a little bit steeper in the beginning. My guess is that the net of these two factors will cancel out when you get ready to resell or trade.
Years ago it was a significant difference between the range of similar vehicles so I think the decision was more difficult. Now, you get a performance car with range that's nearly 400mi which is significantly more than what was considered the range version of the car only a few short years ago. Hell, choice in wheels alone between those two different cars can make up the difference in range whereas you couldn't do that previously even with extreme examples of both due to the significant difference.
Are there other differences between those cars? In other words, does one have a color combo you like a little bit more? Are they both local? Maybe more important of a question from a financial standpoint is what autopilot software does each one have?
Don't get me wrong, on paper those performance numbers between the Plaid & LR are substantial. But in day-to-day use you're not going to be pinning the accelerator pedal to the floor after some time of ownership. This is when the other differences become more apparent but still not worth the price Delta to me anyway. I like to get cars about three or four years old once that depreciation curve starts to flatten out more.
Being as you brought up the financial aspect of cars and seem to have that near the top of your list I would keep depreciation front of mind as you make your decision if you're buying used anyway.
All that said, I'm not sure I would buy either one. Still too much depreciation to be had and it's also the first year of what is effectively a refreshed car or the closest thing to a new generation Tesla Model S since they came out a decade ago. I would argue that this is technically a Gen 3 since the 2016.5 refresh would be a second generation car by traditional vehicle standards given the number of updates. This one is even more significant than that one was as the previous one was largely a re-skinning with a few feature adds. For my financial standpoint, there's some really sweet deals on 2019s and 2020s as people are anxious to get out of them for the all-new car when the performance differences are negligible at best. The 2019 introduced the Raven which had an upgraded suspension in a couple other nice features over the dated SaS suspension in terms of ride quality and most likely long-term reliability. Time will tell on that last part but the ride quality improvements will be something that does stand out from day-to-day use.
Of course your YMMV but that's how I approach most larger financial decisions. I make small sacrifices to have something with a lower likelihood of depreciation. Historically, regardless of make, the largest new vehicle depreciation will be year one, followed by year two then year three. By year 4 that line starts to taper more & you can generally find gems if you're willing to look.
If you disagree with everything I said and end up with either one of those 2021 Model S's, well... That doesn't suck either.
