Teams allows you to send instant messages to individuals in addition to conversations within a Team.
Select Chat - type in a name or names and write your message. You can send a message to anyone in your organisation. The message area looks exactly the same as in conversations so you can add formatting, attach a file, add emojis, stickers, plus schedule a meeting if the chat is for more than one person.
Microsoft Teams - chat feature
At the top right you have options to start a video chat, audio chat, share a file, or add another person to the chat.