This is a Minecraft client mod for Forge that adds local timestamp to text messages received in the game's chat. The mod will also print current Minecraft day & moon phases when they change (can be configured using Forge mod config interface).
Download release jar file and move to the "mods" directory of Minecraft.
UI not yet available for 1.16 (see MinecraftForge/MinecraftForge#7395)
Configuration is saved in file "config/dateandtime-client.toml". Configuration is automatically reloaded when file on disk is changed.