Minecraft wiki entry for Debug_screen, associated text: F3 + D : Clear chat history. Does not include recently typed messages and commands from ↑ and ↓.
F3 + F : Increases render distance by 1 (must be between 2 and 32).‌[until JE 1.19]
F3 + ⇧ Shift + F : Decreases render distance by 1 (must be between 2 and 32).‌[until JE 1.19]
F3 + G : Toggles visibility of the chunk borders around the player.
F3 + H : Toggles visibility of IDs of items, durability of tools, and armor hexcodes for color. It also shows the scale of maps and details of a firework rocket in a crossbow.
F3 + I : Copies server-sided block or entity data to the clipboard.
F3 + ⇧ Shift + I : Copies client-sided block or entity data to the clipboard.
F3 + N : Cycle between Spectator mode and the previous gamemode. Switches to Creative mode if there is no previous gamemode. Requires cheats to be enabled.
F3 + P : Toggle automatic pause when Minecraft loses focus on / off.
F3 + Q : Gives help and shows all F3 + key combinations.
F3 + T : Reload textures, models, sounds, and any other resource pack contents.
F3 + F4 : Opens gamemode switcher menu. While holding down F3, a player can cycle between the game modes by pressing F4 and enter the selected gamemode after releasing F3
F3 + Esc : Toggle pause without pause menu (if pausing is possible). Singleplayer-only.
⇧ Shift + F3 : Opens the debug screen with the profiler graph.
Alt + F3 : Opens the debug screen with the Frame time graph.
(note that both graphs can be opened with ⇧ Shift + Alt + F3)
Alt + 5 : Brings up command shortcut menu (Realms Only)
F3 + L : Generates Performance Metrics