Please note that there is no fixed lot size limit across all instruments. Maximum lot size varies by the specific pair or instrument being traded.
You can check the contract specifications in your trading platform for the exact limit on your chosen instrument. As long as you have sufficient margin and remain within your risk parameters, you may open positions up to the maximum lot size allowed for that instrument.
Before placing large positions, ensure that you fully understand the margin requirements and specifications of the instruments you intend to trade, as these can affect your ability to maintain multiple open positions simultaneously.