Explanation for unknown message sent from me.

You might want to change your passwords immediately.

Good luck! 👋🏼😉

"Explanation for unknown message sent from me.: Just now, I was sitting at my desk using my PC, I then got a text (iMessage) from someone that I haven't spoken to in a while, When I unlocked my phone and went to the messages with that person, I saw that I sent a message 1 minute before opening my phone with simply their name. But I hadn't even been on my phone. [...]Is there any logs or other ways I can figure out how this message was sent? or what device it was sent from?"

-------

Log into your Carrier's Site:

Apple does not keep a log of deleted messages' information. So, log into your Carrier's site, and see if you can see this in you account. Logging in myself, I can see a message log and call log going uptown 90 days back.

"It's not a deleted message, It's still there and it's an iMessage so it won't appear as a text message."

-------

Pending iMessage:

It was probably pending from another device. Does anyone else have access to your devices? Having turned on your iPhone, it would show up then.