Different tones of colour

The top one looks like she just put different diluted blues and purples in a very unarranged manner. the whitish bits are probably due to the diluted blue and purple toning very pale hair white rather than taking up color. I think it is trail and error, you just put the colors wherever and hope for the best. I did something similar with spring green on the roots and lilac on the ends with a few flamingo pink bits here and there. at first it looked weird but once it started to fade it looked really nice and blended.

the second photo to me looks photoshopped. If you look closely at the forehead area, you can see a tiny bit of the color overlapping with the skin. I might be wrong though.

you could easily get the effect of the 2nd picture by doing your hair a random mix of purple and pink all over and then get highlights with a low peroxide to get blonde/pastel colours

Ahh yes it does look shopped. Whenever I do my hair it tends to all be the same shade so I shall have to take the plunge and see what happens!

Whenever I had something like that, I'd just use different dye mixes and just randomly apply them all over - I'd usually just apply one as a base colour and leave some sections and then I'd use the other dyes on those bits. If the shades were similar, I'd usually layer them in places as well. Hope this helps you even though it's really hard to explain 🙂

I get that multi-tonal look in the second pic over the base I have. Instead of just flat bleaching  I used a combination of highlights and bleach bathing to gradually lighten from medium brown. The highlights were different blondes too, so there are lots of shades in my hair from white blonde to yellowy/golden blonde at the darkest parts. It gives a much more natural effect, even with unnatural colours.
Not much help if your hair is already bleached, but maybe an idea for the future.

The first photo is what I kept getting down to from mixed blurples and once wildflower AS LONG as it was toned.

I think some pictures you find like this are just unintentional, a happy mistake. The effects of different dye mixes on different levels of base in varying stages of fade.

It could be achieved with putting a colour over a highlighted base oor highlighting the hair with different shades of the same colour.

I think some  are also photoshopped