Iphone won't turn on

My iPhone 8 is stuck on the apple logo and won't turn on. I did not update it or anything and it has no update bar underneath it is just the apple logo. sometimes it turns off to a black screen and then turns back on to the apple logo I've tried the restarting methods but pressing the volume up then volume down buttons and then holding the power button, it turns off then on but stilll shows the apple logo and it is stuck on there.

how can I fix this