Instead of risking a fixed number of points, the trader risks, say, 1.5 times the 14 period atr. In a quiet market that is a tight stop in absolute terms; in a volatile one it is wide. The noise level, not the account, sets the distance.
Combined with position-sizing, this keeps risk per trade constant in currency terms while the stop distance varies: a wider ATR stop simply means a smaller position. That pairing is the standard professional approach.
The weakness is that ATR measures recent volatility, so it is slow to react when conditions change abruptly. Entering just before an earnings report or a rate decision with a stop sized on quiet-period ATR understates the risk badly. Event awareness has to sit on top of the arithmetic.
Related: atr, chandelier-exit, position-sizing, invalidation-level, true-range