NO, it's not actual President Trump texting you. In fact he will never have that direct power. That is a good or bad thing depending on your political opinion. That's why twitter exists anyway. haha.
HAPPENS at approximate at 2:18pm
Today(Wednesday) is a big and IMPORTANT test in case of any emergency. It's called a, "Presidential Alert" and about 225 million phones will get a text message. Here is a good breakdown of what will happen. CLICK HERE (Yes, that's a link to CNET and I'm a geek that gets news from a technology website shut up)
But unlike the emergency alerts and AMBER alerts that you can toggle off on your smartphone, you won't be able to switch off the notification for this "presidential alert," which is designed to be used "in the event of a national emergency," the Federal Emergency Management Agency says.