How to request the character to switch levels?

So I’d like so that when the player character reaches for example a door (when he’s close to it), a text appears asking the player for example to press “E” to go to the next level, how can I make that trigger?

for this, you can had a trigger volume in your level, just after the door. then in your level blueprint, you can use the “on actor begin overlap” to trigger the functions you need.(display the press button widget, then opening the level ( using the open level node or with console command.
hope it helps