None of the big name stores seem to carry them and I’d prefer not to buy online cause I can’t feel them first. Anyone know stores that have them?
According to this (床尺寸 - 维基百科，自由的百科全书) and this (歐規、日規、美規和台規床墊尺寸全解析！ - Lunio Taiwan) a California King, known as 加洲特大 or 雙人加大 in Taiwan, measures 183cm x 213cm. The Taiwanese size “king” or 雙人特大 is 182cm x 212cm and is a standard size here. These seem to be compatible as there’s only a 1cm difference.
The standard Taiwanese king size sheets should be available at most mall bedding shops and other home stores like Ikea, Muji, Nitori, HOLA/特力屋, etc. Or search 床單 on Google Maps.
I didn’t see any at IKEA, but I’ll look at the others.
King size at IKEA in Taiwan is 200x180. That’s also the size at Zara. That’s short of a California king in both directions, but especially length-wise. I’d be quite surprised if you can find that size in a brick and mortar store here.