This is an article on how to change the protagonist's name (player's name) in NieR Replicant (Remake/PS4). It covers whether you can change the name after setting it once and the origin of the protagonist's name.
Table of Contents
When to Enter Your Name & Can You Change It?
You Can Only Enter It Right After Starting the Game

The protagonist's name is determined when you enter the player's name at the start of the game. You can only enter it once, and the player's name becomes the protagonist's name.
The Protagonist's Name Doesn't Change the Story
The protagonist's name does not affect the story's progression. Feel free to play with any name you want to use.
Cannot Be Changed Later
Other than the initial entry at the start of the game, you cannot change the name after you've begun playing. If you really want to change your name, you will need to create a new save file from New Game.
Origin of the Default Name and Trivia
The Name "Nier" Comes from the Art Book
The protagonist of Replicant's common name is not mentioned in the game or on the official website. Nier is listed as the official name in the art book, and now it is common to refer to the protagonist as Nier.
The Village is Named After the Protagonist

The protagonist's village in the game will be named after the name you entered at the start. On the map, it will also be displayed as [Your Name]'s Village.
About Name Restrictions After Endings
Name Becomes Unusable After a Certain Ending
In "NieR Replicant," after viewing a certain ending, you will no longer be able to use the same name to create a new save file.
Save Data Can Be Restored in Ver. 1.22
In the new "Ending E" added in Ver. 1.22, your save data is restored after clearing it. Of course, your name will also revert to the original one, so you can play Ver. 1.22 without worry.