Hi, my server is on 1.18.2, and i want to put on 1.16.1, how i can do that

You can download legacy paper here https://papermc.io/legacy

You just have to download the paper version that you will use from the page https://papermc.io/downloads/all change the name to server so that it is server.jar go to files delete what you have there and upload the server.jar and if you have the eula and server.properties too and start the server like this it should work at least it worked for me