Well, 'Grimgar of Fantasy and Ash' could be considered similar. It's about a group of people in a fantasy world trying to survive and grow stronger, just like the characters in 'memoir of the king of war light novel'. 'No Game No Life' is also a great pick. The main characters in this light novel are highly intelligent and have to use their wits to navigate a world ruled by games, which is somewhat similar to the strategic elements that might be present in 'memoir of the king of war light novel'. Additionally, 'That Time I Got Reincarnated as a Slime' has a protagonist who starts from a weak state and gradually becomes very powerful, which could be a common point with the 'memoir of the king of war light novel'.
There are quite a few light novels that might be similar. For example, 'Re:Zero − Starting Life in Another World' has a complex story and a main character who has to face numerous challenges, much like in 'memoir of the king of war light novel'. Also, 'The Rising of the Shield Hero' is about a hero in a different world with his own battles to fight, both physical and against the prejudices of the people around him. 'Konosuba: God's Blessing on this Wonderful World!' is a more comedic take on the isekai genre but still has elements of adventure and growth like the 'memoir of the king of war light novel'.
One similar light novel could be 'Overlord'. It also features a powerful protagonist in a fantasy world. Another is 'Sword Art Online', which has elements of adventure and a strong lead character. And 'Log Horizon' is also a great choice as it shares the theme of being in a different world with unique abilities.