Up to 66.6% LTV you can do whatever you want with the additional money. So if your property value is 1.2 million and your current mortgage is 500k, you could increase it to 800k and buy a Ferrari for 300k. Or invest 300k in stock ETFs. Also the same with properties without a mortgage. You can go to any bank, let them make a valuation of it and then you can make a new mortgage up to 66.6% and use the whole amount however you desire.
As soon as you surpass the 66.6% LTV, there are more restrictions. Usually only possible for RE-related things. So renovations or generating capital for buying something additional. Also repaying a 2nd pillar withdrawal that you made for RE in the past.