At the very start of the Reclamation Day main quest in Fallout 76, you must create your avatar (picture1). This step is purely cosmetic and does not influence the course of the game. Similarly, if you choose male or female, the names of some gender-related skills will change, but the effects will remain the same.
With the character creation tool, you can choose a predefined face from those offered (picture2). By selecting “Face”, you will be able to sculpt the different parts of the face, change the color or select new parts (pictures3and4).
By selecting the “Extras” option, you will add/remove makeup, hair, or other elements such as stains, imperfections, dirt,... (picture5). Finally, by selecting the "Body" option, you can change your character's corpulence.
These choices are not final. If you want to modify your character during the game, it is possible. At any time, open your map, go to the options and select “Change Appearance” (picture6). You will be able to completely recreate your character if you wish (picture7), and even change his gender.