Before using any of the console commands i recommend creating a config file. There a some commands that are mentioned in this guide that doesnt save when you restart the game.

To do this, go to Quake II game files by right clicking on quake 2 on steam and click on 'Browse local files'. When the folder is open go to 'rerelease' and to 'baseq2'. Create a text file with the file extension being 'cfg'. Once you created the config file and added the commands you wish to save, go to the launch options on quake 2 by right clicking again and go to properties. And on the text box of the launch options add '+exec your_config_name.cfg'.

After you done all of that, it should not reset any console commands that you changed anymore.

clear - Clears all console text.
g_showintromovie "<value>" - Skips(0/1) the intro videos and goes straight to the game menu.
con_showfps "1" - Displays(0/1) current FPS at the top right corner of the screen.
cl_engineFPS "<value>" - Sets a custom max fps value.
sensitivity "<value>" - Changes the sensitivity of your mouse.
snd_mastervolume "<value>" - Changes the volume of the game from 0 to 1.
snd_volume "<value>" - Changes the volume of the game sound effects from 0 to 1.
s_bgvolume "<value>" - Changes the volume music of the game from 0 to 1.
r_brightness "<value>" - Changes the brightness of your screen from 0 to 2.
cl_run_0 "<value>" - Enables(0/1) option to keep Always Running.
r_skipUnderWaterFX "<value>" - Disables(0/1) water effects when your underwater. Preview[imgur.com] (You can also customize the underwater effects if you want with these commands: r_underwater_strips, r_underwater_magnitude, r_underwater_speed, r_underwater_spread)
cl_muzzleflashes "<value>" - Enables(0/1) weapon muzzle flashes.


r_bloom "<value>" - Enables(0/1) bloom. (You can also customize the bloom if you want with these commands: r_bloomBlurRadius, r_bloomThreshold)


con_fontsize "<value>" - Changes the font size of console text and also some other text for example fps text(if you have con_showfps set to 1 of course). Default value: 14.
con_fontsize "24"

con_fontsize "16"

con_fontsize "12"

con_fontsize "8"


r_rhirenderfamily "<render>" - Changes the render of the game. Choose between "vulkan" or "d3d11"(DirectX 11).
net_nerdstats "<value>" - Displays(0/1) network/stats information when playing in a multiplayer deathmatch/coop lobby.

cl_skipHud "0" - Disables(0/1) hud.
scr_safezone "<value>" - Changes the hud safe zone.
scr_scale "<value>" - Changes the hud scale from 1 to 5.

fov_0 "<value>" - Changes the Field of View value from 1 to 141.
bobskip_0 "<value>" - Disables(0/1) the bob movement camera.
hand_0 "<value>" - Changes(0 - Right / 1 - Left / 2 - Removes) the weapon to the right side or the left side.


These three console commands allows to customize the position of the viewmodel. Try to mess around with these to get something you like. (Keep in mind that in multiplayer unless your the host, these will not work.)
gun_x "<value>" - Goes right or left.

gun_y "<value>" - Goes foward or back.

gun_z "<value>" - Goes down or up.

crosshair_0 "<value>" - Changes crosshair. There are 29 crosshairs on total. Setting the value to 0 removes the crosshair.


(Not all 29 crosshairs are here. These are some of them to show.)

crosshaircolor_0 "<value1> <value2> <value3>" - Changes crosshair color. The three values correspond to Red, Green and Blue. It goes from 0 to 1.
crosshairscale_0 "<value>" - Changes crosshair scale.
cl_skipCrossHair "0" - Disables(0/1) crosshair.
scr_hitmarkers "<value>" - Enables(0/1) hitmarkers.

If you want to more console commands there are a bunch of websites and steam guides that tell you all the commands and what they do. Or you can just type "help" in console and it will show you all console commands.