I think your confusion comes from the fact that there is more than one way to use particles for an emphatic effect.
Sentence final particles
Sentence final particles よ, ぞ, ぜ, わ and others are sometimes called emphatic particles. They are added to the end of a sentence for an emphatic effect — for example, conveying that you feel strongly about something.
Sentence final particles usually emphasize the statement of the whole sentence.
There are many such particles, although よ is particularly common and versatile. Choosing between such particles will depend on nuance, register, gender, etc. and there are many questions about these:
Also see the tag sentence-final-particles or the individual tags particle-よ, particle-わ, etc.
The particle も can be used to emphasize a particular word within a sentence.
For the emphatic use of も the プログレッシブ和英中辞典 lists following example sentences
This (article) cost no less than [all of] 10,000 yen.
It took him ten long years to complete it.
All ten people made the same mistake.
I don't know a single one of the villagers.
You are carrying your joke too far.
When it's as hot as this, I feel listless.
It was simply too thoughtless of him to do such a thing.
Why didn't you let me know earlier? I'm surprised at you.／How could you not have told me?
We sang and sang until we had finished fifty songs.
I waited for a good three hours.
Similarly, the particle さえ can be used for an emphatic effect. Again, the プログレッシブ和英中辞典 lists the following example sentences
On top of that [everything], it began to rain.
If even he doesn't know, then nobody does.
He can't even write the alphabet.／He cannot so much as write the alphabet.
There is not a drop of water (to be had [found]).
He was betrayed even by his own brothers.
If only you had studied harder, you could have passed the examination.
This is all I need.
Contrastive particle は
The particle は can also be used for contrast/emphasis. See for example
Combining "emphatic particles"
Of course there is no reason you cannot combine sentence final particles and emphatic も or さえ — just pick any of the above example sentences and add an "emphatic" sentence final particle.
Other expressions used for emphasis
On top of that, there are other words or expressions used for emphasis. For example