The LG UltraFine 5K displays require two DisplayPort connections to support 5K. A Thunderbolt controller only has two DisplayPort connections. Therefore you will not get more than 4K from the 5K display if it is daisy chained to another Thunderbolt display. Since the 5K displays take two DisplayPort connections, they do not have a second Thunderbolt 3 port for daisy chaining, so they must be connected at the end of a Thunderbolt chain.
You can daisy chain two 24" LG UltraFine 4K displays, no problem. Or one 24" LG UltraFine 4K and one 21" LG UltraFine 4K (the 21" goes at the end of the chain because it is not a Thunderbolt display).