A few years ago, I made a Telegram bot that I use daily to remind myself things I have to do: https://t.me/remembr_bot

You basically send it a message that says : "Pay water bill in two days at 9am", and it will send you a notification that says "Pay water bill" in two days, at 9am. You can also easily snooze notifications using handy quick-actions buttons.

It's free btw, anybody can use it.