If you don't trust trainers, you can manually cheat using (v7.2 or later). This was a highly popular method in mid-2021 because it worked across all patches.

To activate cheats, press the key to open the console during gameplay. Enter your command and press Enter . Note that unit names must be entered in all lowercase for the console to recognize them. Essential Console Commands

(updating)Mission guides, gameplay basics, unit basics and Small tips