21.5 " iMac External Monitor

[1949William]

I'm looking for a monitor to go with my 21.5" iMac. I tried as Asus (a cheap one) at one time, but could never get the colors to match my iMac. I have been using an older iMac in target mode, but when I get a new iMac I know it won't work that way anymore (also would like to hook my wife's Macbook Air M1. I am restricted by the space I have for a monitor and am wondering about the UltraFine 4K Display on Apples site. It's a bit more than I was planning on spending, but if the color matching is good I might go for it. Any other thoughts - suggestions.