Firstly lets list some firepower feats,

• [Megajoules] Firstly a Borg sphere manages to put out some megajoule range firepower against a settlement where there is zero reason for them to hold back.

• [Gigajoules] [The NX-01's phase canons are rated at 500 gigajoules. (ENT: Silent Enemy)

  • >REED: This, ladies and gentlemen is a phase-modulated energy weapon. It's rated for a maximum power output of five hundred gigajoules. Enterprise was designed to carry three of them. We have one, and it's only a prototype.

• [Terajoules] Tying in with the previous feat they figure out how to overload the system by a factor of ten without damaging the ship later in the episode (ENT: Silent Enemy)

• [Petajoules] This is the classic, the (non-canon but pretend I didn't say that) TNG tech manual states that a photon torpedo's warhead is 1.5 kg of antimatter. Easy E = mc² calc gets ~270 petajoules per torpedo.

• [Exajoules] I have seen this feat from TNG: Skin of Evil calced at a minimum of 500 Mt which happens to be ~2 exajoules (though I have also seen it calced higher) (The calc is in here)

• [Zettajoules] A feat from DIS: Perpetual Infinity where Discovery bombards a planet with six torpedoes. This was calced on SB to 2.6 zettajoules per torpedo.

• [Yottajoules] A small fleet destroys 30% of a planets crust in a single volley.

• AND BEYOND In TOS: Obssession the Enterprise does this to a Earth like planet with a hand held antimatter bomb.

• I could go EVEN FURTHER BEYOND but I am getting board of making the list.

As you can see, it is really clear and there should be absolutely no confusion regarding how powerful Star Trek ship weapons are.

No matter what range you pick, it is contradicted by most of the other quantifiable feat in the damn show. This isn't like Batman fluctuating between a one tonner and a twenty tonner with a billion feats in between. There is a very limited pool of quantifiable firepower feats in Star Trek. MOST of the time they are shooting at random ships which isn't something you can compare across to a different setting as we don't KNOW how durable the target is unless it is one of the rare cases we get numbers get stated. But due to the fact they are spread across a wide range none of the feats are really statistical outliers (well actually there is one feat in particular which is definitively an outlier). Sure, if you don't know all that much about Star Trek I can post The Die is Cast Skin of Evil Perpetual Infinity The Wolf Inside Obsession to make it look fairly consistent but that is basically just lying by omission and not telling the whole story.

The other other problem is that most of the higher end ST feats have some random issue which tosses a few question marks into how legit they are.

• The Wolf Inside: It was done by a spore powered super ship.

• Perpetual Infinity: The plasma reactor at the site they hit.

• Obsession: They were blowing up a warp capable random life form.

• Skin of Evil: Shuttle's antimatter (?) power plant.

• TDIC: weird sensor and visuals readings.

You can get some millage out of the idea of "dial-a-yield" weapons (which is supported in the show (ENT: some episode early in the Xindi arc in particular)) but even then there are plenty of times where they "should" have been able to throw around bigger booms more easily but they don't or where they should be able to effortlessly survive things but they don't.

Star Trek is like this for just about all of its ship stats though most are less variable.

I will also fully admit I am being a bit disingenuous by including Enterprise era feats to TNG and arguably First Contact. But then again First Contact isn't the only time we have seen super low torpedo yields with orbital bombardment (the movie with "god" in it, Star Trek 5 I think?) and if you are a fan of the Tech Manuel the galaxy class' phaser bank has a output of something like five megawatts or a few gigawatts depending on how you interpret the passage.