Just a few suggestions:

Have a way to turn chat off, like if theres too much spam and don't want the chat taking up the entire screen, have a /chatstfu option (I know that there are many servers that have it)

Have it so that people in plots have a separate chat than those in the prison

BACKPACKS so that we can carry more in our inventory

Please take these into consideration
-coffeandbacon

 

No support. There is already a way to turn chat off in Vanilla Minecraft (Options > Multiplayer Settings > Then edit the "Chat" button to "Hidden" or "Commands Only"). There is no real point in having a different chat for plots and the actual prison world. I don't really think backpacks are necessary when you get one free player vault (can be accessed by the command "/pv 1") and you get enderchest storage like usual.