This is to enter or create high levels of heist, difficulty such as Overkill or Overkill 145+, if you have level 145 and you need 193. If you want, then click Play -> Online, then search for games, and there will probably be servers with high difficulties. But if there is a player with a reputation higher than yours, then most likely he will help you, you can also create your own lobby, just click create lobby and then you yourself choose what kind of heist you want, turn on bots and etc, and after that wait for players or invite your friends and start heist. I also recommend if you are a beginner from 0 to ~ 80 reputation, then play on a hard level of difficulty, and if from 100 to 145 (possibly lvl 193 reputation if you purchased a Wolfpack) then you can safely play on Overkill and even Overkill 145 +.

This is to make the secret Overdrill (sometimes Overvault, if you will). If you don't know what Overdrill is, guides and internet will help you. With this method, you can quickly get 30 ~ 45 reputation or above. But you will need 40-45 minutes to complete this secret.
If you don't know how to do it, I advise you to read this guide -> OVERDRILL GUIDE
Made by macsleggemek.

Third way (worst way of all)
And so, as you probably already understood, this method is cheats. None of the creators of this guide encourages the use of cheats, and on the contrary, cheats are the worst way to play any game. Remember that you are playing this game with pleasure, not to spoil other people’s pleasure. Respect other people's space and opinions.

Well, or if at all, I apologize for this word, a idiot and like to spoil the game for other people, then please. I, perhaps, will not describe the functionality of trainers, because on the Internet you can find everything about cheats yourself.