In smaller cities, fourplexes would still be allowed anywhere, if one of the units meets affordable housing requirements, and six-plexes would be allowed anywhere in larger cities, provided two of the units are affordable.

Source: https://www.columbian.com/news/2023/mar/07/washington-house-passes-bill-banning-single-family-zoning/

Now, the bill only requires those cities to allow for duplexes, triplexes and fourplexes, and they would only have to allow them in 30% of areas currently zoned for single-family homes.

Source: https://www.kunc.org/news/2023-04-25/major-changes-to-sweeping-land-use-bill-fail-to-win-over-opposition