For the 2021 Toyota 4Runner, the low-beam headlight uses an H11 bulb, while the high beam uses a 9005. The 9005 bulb is also used for the daytime running lights. The supplied fitment data does not identify a headlight-type variation, so these applications should be treated as the listed fitment for this model year.
Other useful exterior applications include 7444NA bulbs for the front turn signals and parking lights, a 7440A for the rear turn signals, and a 921 for the reverse lights. The front side marker uses 168NA, while the license plate lights use 168. The rear brake, center stop, tail, and rear side-marker lights are listed as LED applications rather than replaceable bulb sizes.
Interior lighting varies by location: dome and trunk lights use DE3175, map and interior lights may use 168 or 917, and vanity lights may use 194 or 7441. No fog-light bulb fitment is provided.