The difference between NP1 and NP5

Before I answer your question, you have a mixed and incorrect version of how NP's are worked out.
There are two different traits to an NP; Level & Charge(Overcharge).

For Altria (assuming you're referring to the 5* version), if you have her NP Level at 5 *basically 5 altrias combined* her NP damage will always result in 500% damage regardless of charge. (or 600% with her NP upgrade quest) This goes the same for the NP1-4 variants.

Now there is Overcharge, which is the bonus effects that come with the NP, in this case, her Charge bonus is gaining NP. If you trigger her NP when she's at 100%, she will gain 20% charge. If you manage to get her to 500% with an NP chain, she will get a 50% NP charge instead.

So the answer is no. NP5 will always deal higher damage than a NP1. There will be no bonus damage in NP's unless otherwise stated in it's charge effects.

Bonus: For support NP5's like Waver, NP5 waver will always debuff more defense than NP1 waver.