This Plugin gives you easy Access to Commands like:
/fly <Player>
/flyspeed <Speed>
/god <Player>
/invsee <Player>
And other usefull Commands.
You will need op for most of these Commands.
Open Source, you can use this however you want.
https://github.com/Zaphrie/Zaphrie/tree/Admintools-Plugin-1.17.1