What should I do if I just change my number and get a threatening text message?

Look carefully at the receiving time. Is it a short message received before changing the card?

If not, don't rule out the possibility of your friend playing pranks.

I really don't feel at ease, so I can ask the police station in my jurisdiction for help. If the other party's number is not a black card, you can find the owner. Remember, leave a message as evidence.

Peace/peace/peace.