If it comes to cheats you have internal and external cheats, for external cheat PE format is usually .exe, thus there is just need to run game and after that .exe with the cheat, if it comes to internal cheats there is need to inject such cheat with dll injector, since internal cheats are in the format .dll
For injection you can use extreme dll injector, download it and after that run this dll injector, put as process "cs2.exe", and in settings change injection to standard injection (it should be already as standard injection), after that run game but it with with launch option "allow_third_party_software", this will allow to inject any .dll file with standard injection to the cs2, after that in game press INS key to open menu, for 99%...