Otto never asks for a lot size. It asks for a risk setting and works the lots out for each trade from three things: the fraction of the account the setting allows the trade to risk, the distance from entry to the stop loss, and the value of a point on the instrument at your broker, read from the contract specification at the moment of the trade.
A trade with a wide stop, such as a weekly currency position, gets a small lot. A trade with a tight stop gets a larger one. Each risks the same amount, so a run of losses in one market is not larger than a run in another simply because that market's stops happen to be closer. Each strategy is also scaled to its own risk profile before the portfolio setting is applied, so that a volatile strategy does not dominate a calm one. A hard ceiling caps any single trade regardless of the arithmetic.
The alternative, a fixed lot on every trade, is what most retail EAs offer, and it means the risk per trade changes with every stop distance and never changes with the account. After a losing run the same lot is a larger share of what is left, so risk rises exactly when it should fall. Otto's sizing does the opposite: it shrinks in a drawdown automatically, because the account did, and grows as the account grows.
Two practical consequences. Otto reads point values and contract sizes from your broker, so it sizes correctly on gold, indices and currencies without being told. And on a small account the broker's minimum lot may be larger than the calculated size, in which case Otto does not quietly take more risk than the setting allows; the minimum balance recommendations exist to keep the account above that line.