Subscribe to download
SRPG Studio Official Plugin

1. Launch the SRPG Studio.
2. Steam (Top Menu) -> Show Subscribed Items -> Save to File

Where is the download?

I copy/pasted the $readme.txt included with this below, since the description doesn't say what this is actually for (read in reverse order since Steam puts newest comments first)

highlevel-outside.js
Draw in the unused range in the map.

other-foregroundmotion.js
Even if the motion is passive in a real battle, it is displayed in front of the active.

other-combinationselector.js
Cut a part of the decision processing of the enemy's AI processing.

other-motioncolor.js
Set up the specific motion color in the class, not the unit.

other-unmovableweapon.js
The weapon which lowers the mov cannot be equipped after moving.

system-startup.js
Decide if game.exe is a first startup.

system-interruption.js
Display suspend command.

system-animeview.js
Real motion can be shown with an extra.

window-unitmenubottom.js
Add the 2nd page on the unit menu screen.

window-unitsimple.js
Draw the level and the exp additionally at the window displayed on the map.

window-mapthumbnail.js
Add the entry of "Map Thumbnail" on the battle startup scene.

config-automode.js
Display the details of the "Auto Mode".

config-enemyunitspeed.js
Display the details of the "Enemy Unit Speed".

config-largemapunitwindow.js
"Map unit window" supports large face images.

config-markingdisabled.js
Clear the details of the "Enemy Action Range" and disable the marking of the cancel input.

config-movepointvisible.js
Display the details of the "Display of Moving Points".

highlevel-resolution.js
Change the screen resolution to any given value.

highlevel-canvas.js
Draw a rectangle.

custom-unitevent.js
Make Battle Unit Event permanently executable.

custom-conditionalshow.js
Change the visual of the class to picture.

custom-conditionalshowex.js
Change the visual of the class to the original effect.

scriptexecute-eventjump.js
Jump to the specific event.

scriptexecute-communication.js
Delete the window of the communication event.

scriptexecute-customparameter.js
Retrives the value in the unit custom parameters.

scriptexecute-equipunitweapon.js
Equip the specific weapon possessed by the unit.

scriptexecute-objective.js
Create an event command to indicate the victory condition.

scriptexecute-demomap.js
Display the opening event of the specific map at the base.

eventtrigger-unitcount.js
Decide if the total amount of specific armies is less than the certain number.

eventtrigger-quest.js
Decide if the current map is a quest.

eventtrigger-firstskill.js
Decide if the specific skill has been firstly activated.

From $readme.txt:

Please copy the official folder in the Plugin folder of your project
so that the Plugin reflects in your game. For files which you want to ignore,
delete them or put $ at the beginning of the name of the file.

custom-unit.js
Add the "attribute" parameter on the unit.

custom-class.js
Set critical correction in the class.

custom-classfootstep.js
The class's custom parameters determine the footsteps as the class moves the map.

custom-weaponmusic.js
Change background music if a specific weapon was used for battle.

custom-item.js
Create the item to damage all enemies.

custom-skill.js
Create an activation skill to triple the power.

custom-state.js
Create a state to be more likely aimed by enemies.

custom-npc.js
Set colors of the lines of the npc and the unit.

custom-map.js
Set it so as to display a message after the reinforcements appears.

custom-pattern.js
Create an action pattern to move at random.

custom-placeevent.js
Move the stock item temporarily.

Apparently it's a collection of Javascript files that add different features to your game. The readme in the plugin folder says what each one does. I'll copy and paste the readme into my next few comments.

What does this plugin do? Like what's included? Anybody know?

Steam (Top Menu) > Show Subscribed Items > Save to File