What is the size of a point? Or, what is a particle?

[apeiron]

To address your "temperature" model, first of all this has nothing to do with what we consider as "hot or cold". This is a subjective sensation and has nothing to do with physics. Secondly, there's a difference between (i) a valid model that later on gets enclosed into a more general description versus (ii) a flawed model. Newton's laws are examples of (i) and the caloric/Bohr atom are the 2nd. It does mean that I consider Newton's laws as a valid description of "reality" within the realm of their applicability.

You are begging the question again. What do you mean by valid? Do you mean "true" or do you mean "seems to work".

Or when you say flawed? Does this mean "false", or "does not seem to work so great".

If you are a pragmatist, philosophically speaking (like CS Peirce), then you are taking a modelling approach even if you don't seem to understand that.

Even if you say I believe it to be true at the moment now, but better evidence may change my mind later, you still doubt and thus you still model.

But if you actually think some models are true, some models are false...

Again, define your terms. Cite your literature.

True and false are absolutes. Valid and flawed are clearly pragmatic terms that invoke "fitness for purpose". We can then ask whose purposes? By what measures?

A meta-level of epistemology is being acknowledged that can then be discussed. Rather than your attempts to close down discussion as soon as the issues get too gnarly for you.