Forced liquidation is triggered when the marker price reaches the liquidation price of the held position and the margin cannot meet the margin requirement for position maintenance.
If there are multiple contracts in cross-margin mode, the liquidation price will be calculated by combining the account balance with the margin and profit/loss of each position, and in case of forced liquidation, all positions in cross-margin mode will be liquidated together.
You can calculate the liquidation price by using the Contracts Calculator on the perpetual futures trading page.