Not really a percentage cut off. It's more based on appearance. Something like

75% European/WANA 20% Native American 5% Sub Saharan African

Might be a typical admixture of a latino who would look white. Though I have seen as low as 60% European latinos come out with a "white" phenotype sometimes. The Native American sometimes gets absorbed phenotypically by the European/WANA. Or just makes a Eurasian look that people still count as "white."

On the flip side higher European percents can look not "white." Latinos with more African will have less of a chance of appearing "white"

A person with: 75% European/WANA 20% Sub Saharan African 5% Native American

Chances are this person would probably not present phenotypically as a "white" latino.

Another thing that I have noticed is if the native american and sub saharan african is more evenly split say something like

70% European/WANA 15% Native American 15% Sub Saharan African

The person will appear more "white." From personal observation atleast.

So percent is very rough but maybe a basic idea is something like 70% European/WANA and under 10-15% Sub Saharan African.