When the iMac Pro was my productivity workhorse, I flanked the 5K, 27" display with two 27", vertically-oriented monitors. The iMac Pro's monitor was a
LG UltraFine 5K display (a brief review)
LG 27'' Class UltraFine™ 5K IPS LED Monitor (27'' Diagonal
LG 27 Inch UltraFine 5K IPS Monitor Launched with seamless MacOS
Triple LG 27 UltraFine 5K Monitors
LG UltraFine 5K 27 Display for Mac (Box only, Kotak saja) 27MD5KA
Triple LG 27 UltraFine 5K Monitors
LG 27 UltraFine 5K UHD IPS Monitor with Thunderbolt 3 - LG 27
LG 27MD5KL-B 27 Inch UltraFine 5K (5120 x 2880) IPS Display with
LG 27 Inch UltraFine 5K IPS Monitor - 27MD5KL-B
LG's 5K monitor pushed as MacBook Pro's ideal external display