You can download all plugins from
Curseforge or
Spigot
Simply download the jar files, and put them in your server plugins directory, some of them have config files, just open them with an plain text editor, we invite you to read the plugins documentation file before to know what you need to do.
The main advantage to use plugins over mods is that you only need to install the plugins on the server, allowing your players to join using the default vanilla minecraft client.
Forge Mod Reloader (FML) is used to install mods on your server.
What's the difference between mods and plugins?
Mods allow you to do more than plugins, to deeply change and tune Minecraft, to the point to create an entirely new game experience.
Because of that, mods are much more complex than plugins, need more hardware resources, and are more difficult to set up and configure.
Players also need to install the mods on their Minecraft client to be able to connect to the server, most of the time a specific client loaded is made to make it easier, and to avoid to have to manually install each mod.
The community proposes thousand of modpacks based on forge that combines multiple mods to create entire games based on Minecraft, but with original game experience.
As some famous modpacks: RLCraft, SkyFactory, RAD, PixelMon, feed the beast
Bedrock edition
Minecraft is also available on mobiles, they do not use java to runs the server, you simply have to unzip the bedrock container server files in an empty folder, and starting the server with the bedrock_server.exe file under windows.