Almost, Maruyama said that every 5 levels there is a damage adjustment. So it's almost impossible for a level 10 to beat a level 20 with strategy alone. They could only be overcome and won with races that improve every aspect, like the Dragons, which were practically sub-bosses, with super rare equipment and trump cards like Special Abilities from the Light Novel, Unique Abilities from the Web Novel, or things like Talents and Martial Arts that break the level system.
-Just look at Cure Elim from the extra volume, which, according to Maruyama, if he were level 100 with the exact same strategy, would have beaten Ainz. However, if he changed the strategy to a more planned one while being at the same level and with the same abilities, he would win, or if he had more combat experience, he would also win.