Fleet power console command?

[Royal]

I dont know if im looking in the wrong places of google but is there a console command that sets the fleet power to a certain amount

For example: Changing an early game corvette from 80 military power each to 1 million.

[PlutonArioch]

Since fleet power is calculated and not set, no there is no command to directly set it to a predetermined amount. But there are commands for researching the relevant techs that increase power, as well as commands that add modifiers to a fleet or ship.

For research, there is "research_technology [tech_id]" where [tech_id] is the id of any technology, like better weapons. You can guess them, or look them up, either in the game files or on the internet, for example here: https://stellarischeats.com/tech
This includes repeatable techs that increase all of your ships armor, damage, or fire rate. For Example tech_repeatable_improved_armor_output, tech_repeatable_weapon_type_energy_damage, tech_repeatable_weapon_type_energy_fire_rate... etc pp.
Another easier way would be to use "research_all_technologies [1/0] [###]". The command alone without any parameters gives you all the normally researchable technologies, the first parameter determines if special creature techs are included, the second parameter sets the number of repeatable techs to add. For example "research_all_technologies 0 100" gives all research, excluding special tech, and adds 100 levels of ALL repeatables. Note, this sets the target amount of repeatables, it does not add 100 each time you do the command, to get another 100 you need to put in 200 instead.
To be on the level of fallen empires at game start, use "research_all_technologies 0 10".

Another way to add lots of repeatable techs without researching all other technologies is to use the "give_technology" effect, which can be looped with the "while" effect like this:
"effect while={ count=200 give_technology={ tech=tech_repeatable_weapon_type_kinetic_damage message=no}}"

For modifiers, I have not found a working way to create custom modifiers with commands yet (this used to work), but you can add as many prescripted modifiers as you want. There are a lot of shroud boons that can easily be used. For example "effect add_modifier={ modifier=shroud_weapon_boost multiplier= 1}" adds a 20% damage boost to the currently selected fleet. With the multiplier you can scale the amount.
Note: if you add enough modifiers to get a starting corvette to a fleet power of a million, the games fleet power calculations bug out. I'd recommend to not overdo it that much, having a fleet power of 10k with the starting corvettes is already OP.
You can look at all the available modifiers in the Stellaris game folder under "Stellaris\common\static_modifiers", or create your own with a mod.

I just tested it, and it seems a bit above 500k is pretty much the limit for corvettes before it bugs out. But a fleet of 3 corvettes with a total of 1.5M fleetpower should be plenty OP anyways. Here is the result of a fight against a fleet of 3 OP vs 1000 normal corvettes: https://imgur.com/wK4poAP
I would still recommend to not overdo it, and rather use smaller numbers, but here is the command I used to prepare the corvettes for this test:

effect = {
	add_modifier={ modifier=shroud_weapon_boost multiplier=5000}
	add_modifier={ modifier=shroud_firing_rate multiplier=50}
	add_modifier={ modifier=shroud_shield_boost multiplier=2000}
	add_modifier={ modifier=shroud_speed multiplier= 20}
}

Just select your starting fleet, and paste this into the console. You could also add a timelimit to the modifiers, so they run out after a certain amount of days/months/years. For more information look up the commands here: https://stellaris.paradoxwikis.com/Effects

Oh another thing you can do is to use "effect every_owned_ship={reduce_hp=[###]}" where if [###] is a positive number, it reduces hp of every ship in the selected fleet, and if [###] is a negative number it adds that amount of hp to every ship. If you go over a ships normal hull points though it will reset after a jump or when a battle starts. You can add a few million hull points at the start of, or during a battle though.

[Nova Solarius]

Fleet power don't mean ♥♥♥♥. It's calculated based on the stats but doesn't take into account what those stats actually mean. You could have an armada with ten million FP that doesn't have weapons, and you can win fights against opponents with several times the FP value if you design your ships right.