How to change differential fluid

Pretty straight-forward on your rig; according to the manual you remove the drain plug, drain the fluid, put the plug back in then remove the fill plug and fill it until it is level with the fill hole. I don't know the details of your 4Runner, but here's a general 2022 page giving you information on how to do that.

Replacement (08/2015 - ): Procedure — 2022 Toyota 4Runner SR5, RWD Service Manual ~ LEMON Manuals

I picked the SR5 RWD option at random, but you can get the exact results you need by going to the 2022 Toyota page and clicking on the 4Runner folder.

Free Service Manuals for 2022 Toyota vehicles ~ LEMON Manuals

It'll open up to these choices.

• 4Runner
  • Limited, AWD
  • Limited, RWD
  • Nightshade, AWD
  • Nightshade, RWD
  • SR5 Premium, 4WD
  • SR5 Premium, RWD
  • SR5, 4WD
  • SR5, RWD
  • TRD Off-Road
  • TRD Off-Road Premium
  • TRD Pro
  • TRD Sport, 4WD
  • TRD Sport, RWD
  • Trail, 4WD
  • Trail, RWD
  • Venture

Pick the appropriate one, then follow these links to the instructions specific to you.

Repair and Diagnosis >> Drivelines & Axles >> Differentials & Drive Axles >> Axle And Differential - Service Information >> Differential Oil >> Replacement [08/2015 - ] >> Procedure