Good question.
We will be using chess.com who is very good with detecting bots.
Furthermore I will not allow games longer than 10mins a side. It is very hard to cheat when you have a tight time limit.
Another thing I will monitor is their accuracy percentage. Bots have a 97% to 100% accuracy and unless you are a grandmaster, your accuracy percentage SHOULD NOT and CAN Not be 97% +. Im not saying that I will automatically disqualify such a player based on that evidence alone, but I would have a very close eye on that game and might even ask for help from experts to analyze the game.
At the end I cannot guarentee a 100% honest playfield, just like any other sport, activity, institution, government etc. But I can put measurements in place to minimize it to the point of no significance.
Hope I answered your question.