https://youtu.be/pcX9137EQas?si=DPDZL1wi5P3mWbkb
That video shows how to access the cabin air fan and fit a custom filter. But the custom filters are no longer available (from Russian manufacturing operations that are under export embargo).
I have a 2000 4Runner Limited
I found this forum post from a google search. This company says there is a filter behind the glove box that can be replaced:
Search results: 2 results for "(handle:2000-toyota-4runner-cabin-air-filter-pc5516x OR...
