You can make a decent washed out blonde (grayish-yellow) but not with a real yellow in it like Haley and Sam. And just a few hairstyles even let that color shine through. There are quite a few people online elsewhere who like to discuss using choice language whether that's a real blonde or not (yep, people gots opinions, who knew??) but it's nothing like Sam's or Haley's.
White is equally inaccessible for the identical reasons, the best you get is light gray. The reason is that the details in the Farmer's hair are darker while the details in the Villagers' hair are lighter. You could call these details 'highlights' and IMO that'd be true for Villagers but for the Farmer they're closer to 'highdarks'.
When going for Blonde, I usually choose the following:
15, 99, 99
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You can also do 14 for a little more yellow but it's darker. 16 gets towards green. The recommendation I see online is then to take the second number and drag it to the left but I feel that just desaturates the hair, making it whiter but not really blond-er. I stay with the setup you see here but yeah, that's where the opinions make themselves quite known.
In a similar vein here's gray, definitely not white:
View attachment 30319
Other hairstyles with a decent amount of blondey-yellow showing:
View attachment 30320 View attachment 30321 View attachment 30322
There are a few others with a decent blonde highlight but IMO in those the hair looks light brown/dirty blonde with a decent blonde highlight instead of,
hey are you cosplaying Haley?