now the question is clear (Sie war vielleicht nicht sauber ausformuliert) which you wrote in last lines of your recent comment.
Following is my rough understanding on the matter and I would just like to share. If you are having different opinions, do share.
Based on my understanding from the videos and in general about Li-Batteries, the battery voltage is always a primary indicator of extent to which a battery is charged (State of charge) https://siliconlightworks.com/li-ion-voltage. Ratio of the current voltage of the battery to the maximum prescribed voltage for the battery will give the percentage to which it is charged. (As it is option 1 available in m3, near the battery symbol https://insideevs.com/news/338225/simple-ways-to-extend-your-tesla-model-3-battery-life/). So I believe the battery percentage cannot be wrong because BMS cannot be erroneous in reading a voltage value, otherwise there will be fire all around.
Now anyone can make (not only Tesla) a table showing Battery Percentage Vs. Range. For example, if the battery is at x%, just drive it until 0% and note down the kms travelled. I think this is option 2 available in m3, which is also shown near the battery symbol.
But if you noticed, this estimation does not take into account variables such as driving habits, terrain, etc. So I believe the battery range is prone to false values.
However, when you take all the variable factors also into account, you get dynamically updated range which m3 shows on graph and updates frequently https://www.inverse.com/article/50894-tesla-model-3-charging-without-charger. But is this always correct? Yes and No, because this extrapolation is based on recent inputs (like driving behaviour, temperature etc) but car doesnt know what is going to happen in next minutes (should you drive behind a bus or truck ) ? That is why people find this method helpful than the first option and definitly the second option.
The bolded text might be what you were looking for and
although, method 2 and 3 need not to be explained here but for some reasons, I felt like explaining these will avoid any missing information.