Yes and no. Eaglercraft 1.12.2 can connect to any standard Minecraft 1.12.2 Java server. However, due to technical differences in how connections are handled (WebSockets vs. raw TCP), many servers require a plugin like EaglercraftXServer or a BungeeCord proxy to translate the connection.
Navigate to the Official Eaglercraft Platform and fetch the 1.12.2 WASM-GC zip bundle. eaglercraft 1112 top
wss://arch.mc