I have two 2004 Toyota highlanders. In both I smell exhaust when I idle. I bought both used at different times but pretty sure I noticed this from day 1 in both. Goes away as soon as I start driving but notice it again as soon as I put in park.
You smell exhaust in both , maybe a good muffler shop can find a leak if there is one . That would be the first easy step .
There is exhaust leaking out the end of the tailpipe and depending on the direction of the wind you may smell the exhaust coming though the ventilation system.