This plugin increases your max player limit by demand, it will increase it every X minutes, by X amount of slots, until it has reached the max limit set. All of which is configurable.
"Starting Player Slots": 75,
"Maximum Player Slots": 125,
"Increment Player Slots": 2,
"Increment Interval Minutes": 3,
"Increment When Slots Available": 0,
"Only increment when FPS above": 45,
"Auto decrease again": true
Starting Player Slots -> This will be the max limit the server will start with.
Maximum Player Slots -> Slots will never exceed this amount
Increment Player Slots -> How many new slots should be added after every "Increment Interval Minutes"
Increment When Slots Available -> Only increment when the amount of slots available is equal to, or less than this.
Only increment when FPS above -> Will ONLY increase max slots when the FPS of the server is above this value
Auto decrease again -> Will decrease max slots again when players drop off, in reverse order of increase.