3 rooms to one joining we want to live in the EC

Hello,

We would like to remove 2 walls in the ground floor of our house (BJ 1955) and connect this to a large kitchen / dining / living room. Now the question arises, whether there must be a structural engineer, or whether one can judge it that way. In the current kitchen (outlined in black) the 2 smaller walls are no longer. The two red marked walls are to be removed, the passages in the right wall are no longer available, were probably closed.

In the right-hand breakthrough, we would set up square beams on the left and right and move one in the other, and an iron girder has already been pulled in at the upper wall to the former bedroom.