[World Border]

There's a plugin called "World Border"

It doesn't just creates border it also trims your world into a shape

Description reads:

This plugin is intended to efficiently provide a border for each of your worlds, which only people granted special bypass access are allowed beyond. These borders can be round/elliptic or square/rectangular. As the plugin has been written with performance as the most important goal, it should have no performance impact on your server. Additional world trimming and filling commands are available as well.

 

Link: https://dev.bukkit.org/projects/worldborder

[Accessing Console]

No,unless the server owner gave you acces to console

 

[How do I change the server's version]

found the answer to this: 

 

[How do I change the server's version]

I want to change the server's version from 1.14 to 1.8

Not my minecraft version but the server's version