The model Kluger you are referring to uses an engine with the code-name 3MZ-FE. It uses a timing belt rather than a timing chain, so it requires periodic belt changes. This is especially important as the version of the engine fitted to your car is an interference type. That means that the pistons cannot move freely up and down if the camshafts aren’t also turning and, if the belt breaks while the engine is running, the ensuing collision between pistons and valves will probably destroy the engine.
Toyota recommends a timing-belt change every 150,000km which is actually pretty good compared with many other engines which require a new belt closer to every 100,000km or even less. The other piece of advice is to replace the belt tensioners and water pump while the engine is apart for the timing-belt replacement. It’s a lot cheaper to replace those items at that point, rather than having to open the engine up again down the track.