There are various techniques how to rip textures from games. Depending on the game and console, you might be able to extract the textures from the ROM file. Some emulators have support for dumping textures.
Nintendo 64 Texture Dumping
Some N64 emulators and graphics plugin allows dumping of currently used textures.
The Rice video plugin is available for BizHawk and other emulators. In the Rice settings under Texture Enhancement, enable Dump Textures to Files. Now play the game while the plugin is continously dumping the textures. You might want to visit a specific level first before enabling the option if you're only interested in the textures of that specific area.
In BizHawk on Windows, the dumped textures should be found in %AppData%\Mupen64Plus\texture_dump\<game title> (%AppData% points to AppData\Roaming in your home folder). Various sub-folders with various file formats (BMP, PNG) are created. Now you can search for the textures you are interested in.
Note that many textures, that you might recognize as a single texture, may actually be several texture files, such as a half, third or quarter of the whole image. N64 developers used that "trick" due to to strict size limitations of a single texture. Also, some textures may have a different color than you see in-game. That means, the models are colored and get multiplied by the texture color. For example, the grass and dirt in a game might be the very same texture, just either tinted green or brown.