Hair Growth

Hair growth is a gameplay mechanic in Red Dead Redemption II.

To add to the game's realistic athmosphere, the hair and facial hair of Arthur Morgan and John Marston slowly grow as they explore the game world. This progress can be hastened by consuming Hair Tonics, and beards can then be trimmed to specific styles at any Barber Shop or at the various shaving kits found at the camps put up by Dutch's Gang and eventually Beecher's Hope. Hair can only be cut at barber shops.

Facial hair growth is believed to be tied to chapter progression, and thus maximum beard length may not be possible until Chapter 6; however, this is still uncertain.

Red Dead Online
The player character's hair and/or facial hair doesn't grow in regular gameplay, and instead they can purchase instant styles from any barbershop.

Glitches

 * While the hair growth mechanic is relatively glitch-free, there are several reports of problems with beard growth; While some players report they can grow a stage 10 beard as early as Chapter 2, others report that they cannot grow one even in the epilogue no matter how many hair tonics they consume. It has also been reported that some parts of the facial hair grow faster than others, most often the mustache.