//Discord.js v13
client.channels.cache.get(channelID).send({ content: "Mesage goes here" })
client.channels.cache.get("<channel>").send("<message>");
client.channels.cache.get("channel ID").send("hello world");
client.guilds.cache.get("<id>").send("<msg>"); // used for specific channel
const channel = client.channels.cache.get('Channel Id');
channel.send({ content: 'This is a message' });
const channel = client.channels.cache.get('id');
channel.send('content');
const user = <client>.users.cache.get('<id>');
user.send('<content>');
const channel = <client>.channels.cache.get('<id>');
channel.send('<content>');