There should be a randomisation mechanism in the facial features of new settlers, as well as much more different hairstyles for settlers.

Right now, all the male and female settlers have the same 3 or 4 faces, haircuts, and voices. I often see "clones" of the same settler. It would be far more immersive if they had individual and more uniqueness to them, and also the ability to give them nicknames (rather than seeing 'Settler' or 'Provisioner').

Or an even better alternative is having the ability to select a settler and have the settlement's doctor perform facial reconstructive surgery on them (which would just trigger the character customisation application; so you can add tattoos and facepaints etc). For haircuts, greater customisation can also be achieved by having a barber who can cut villagers hairs into the style / colour that you want.

Further, the clothes shop in the settlement could also act as a "tailor" and dye clothes different colours or give clothes a set of predesigned insignias. Or just sell unique "settlement only" clothes that are not found elsewhere in the game.

Finally, it would also be cool if you can make this settler as your companion. Obviously there will be no unique quests associated with such a companion, but perhaps they should be able to perform basic companion commands.

i like most of these ideas. i would settle for giving them clean faces. they're gross. i would understand if they were homeless drifters, but i have clean water for years. and soap.

The dialogue after surgery could imply that they are glad they had the surgery because a raider gang / the institute were looking for them, or something along the lines of that.

It makes zero sense why they would still have dirty faces even after moving to a settlement with clean water. Would be a nice touch if they have dirty faces after working the fields or using the scavenger works station, but then they use the water pump after working, which should clean their faces. Would also be cool if their faces got progressively dirty if the settlement's water level doesn't accommodate the number of settlers.