You can use the below guide on how to change your dino's max level without using a mod.
Step 1: Change Settings in the GameUserSettings.ini Config File
The settings are found inside the file GameUserSettings.ini config file. You can access it by clicking on Configeration Files on the left side of the panel and then click text editor on GameUserSettings.ini
Once the file is open look for the below 2 lines (if for whatever reason they are not there you can ADD them yourself)
Step 2: Editing the values
The reason you want the DifficultyOffset on 1 is it will make your life alot easier if you want to change the dino levels, read below.
Set OverrideOfficialDifficulty= to a value from 1.0 to 10.00.
With the DifficultyOffset from above set to 1.0, each point in OverrideOfficialDifficulty will increase the max level of the wild dinos by 30 levels, and the loot will also be +100% better. So OverrideOfficialDifficulty=3.0 would make max level dinos of 90 in your game, and loot would be potentially +300% higher quality level. A difficulty of 5.0 is the highest difficulty normally found on official servers, and can make creatures up to level 150 (and +500% loot quality).
Step 3: Do a dino wipe
All the dinos on your map (the wild once) need to die and respawn, quickest way to do this is by clicking on the "Wild Dino Wipe button" on the left side of the screen or you can log into the map and manually do this as a admin.