Most of the default LOTRO commands, are listed on this link: https://lotro-wiki.com/wiki/Commands .
LOTRO allows you to customise many commands and even create a few with the Alias feature.
Alt + R opens the in-game filter windows. This allows you to filter out specific quests and their subsequent reminders. It can also be used to ignore unwanted loot. I use it to avoid loot boxes that frequently drop and fill your bags. It can also be used to filter out specific in-game sounds. This is especially handy if you find certain sounds annoying, such as Minstrels constantly yelling or the incessant whinnying of horses at stables.
Alt + F10 (Cycles torch light: forward facing > omni > off. NOTE: Only available inside or during night-time!) If ALT -F10 does not work for u try Win-Alt-F10 (needed with some graphics drivers)
Usage: /played - Displays how long you have been playing a particular character
Usage: /servertime – LOTRO servers operate on Eastern Time.
“Daily” timers reset at 3:00 a.m. server time. Server Time is Eastern Standard Time (EST) in winter or Eastern Daylight Time (EDT) in summer, but is always the time as shown in “/servertime.”
Usage: /ui layout <load|save> <filename>
Example: /ui layout save FredsWardenUI
You can save your user interface and load it at other characters or other computers
Usage: /shortcut <hotkey> <command>
Examples: /shortcut 43 /follow, /shortcut 25 /cheer’
Assigns a slash command to a hotkey.