Yes. 5w-20 is equally suitable for 1KR-FE.
There are 02 oil grades for 1KR-FE as per latest owners manual for Japanese Vitz 2018; 0w-20 and 5w-30. 5w-20 and 0w-30 oil grades do exist by many brands, and these oil grades might also exist in Japan and equally fit between 0w-20 and 5w-30, but Toyota has not mentioned these 02 oil grades in the manual.
It is better to stick with OEM recommendations; 0w-20 or 5w-30, but I believe, 5w-20 will also be equally good. Its properties will be close to 0w-20, but on a slightly higher side (But lower in comparison to 5w-30). As per oil thickness; 5w-30 > 5w-20 > 0w-20 (from thickest to thinnest)
I have been using Total Quartz 9000 future series 5w-30 in my ex-ride, Passo, but couldn't manage it from Pakistan Oil Store, Lahore in 1L or 3L packing (I have explained the reasons in some of my posts). It was my first choice, but since it could not be managed, I had to settle for this and is equally good! It is the most common choice of Vitz owners in Pakistan.
5w-30, API SN / SN Plus, Fully synthetic engine oil from Total Quartz 9000 Future series is best for bucks, for 1KR-FE, and I always recommend it for 1KR-FE and most of the used JDM cars. If you are using it, stick with it!