Does the eave height also apply to bay windows?

Subordinate components... are they always mentioned in the development plan?
And dormers... #6 is a dormer, also a subordinate component...
Just ask your building authority!

Do you also have to observe the eaves height there, since roof structures are not explicitly excluded in the development plan?

Roof structures do not have their own eaves height and are usually exempt from roof pitch requirements – only rarely are special requirements for dormer roof pitches and ridge directions specified.

What about roof structures then (see attached photo)?

However, you really have to decide whether you are asking about "roof structures" or "see attached photo": a dormer is a roof structure; but the one in the picture is more likely a cross gable: at the lower edge of the picture you can see a single row of roof tiles aligned with the roof overhang, but the front of the (then only supposed) structure continues the exterior wall of the floor below. This difference may escape a superficial glance, but in my opinion prevents the legal classification as a "roof structure."

From my point of view, the example is therefore more of a roof penetration than a roof structure and must accordingly comply with the height limitation equivalent to the eaves height for wall height.

Of course, there are bay windows also in attics

OK, there are bay windows also in attics. Whether it is a bay window in #4 is not clear from the picture. I rather suspect a dormer. But it doesn't matter, because even if it were a bay window, it is no longer subordinate and thus I tend to consider it impermissible. However, the development plan in §3 (6) abolishes the eaves height for setback floors, so a strong-arguing architect might also get a dormer approved by the building authority.

Does the eaves height have to be observed there as well, since roof structures are not explicitly excluded in the development plan?

No, if it really is a roof structure and §2 (5) of the local building regulations from the development plan is observed.

Subordinate components... are they always mentioned in the development plan? And dormers... #6 is a dormer, also a subordinate component... Just ask your building authority!

I am also wondering whether the eaves height of subordinate components actually has to be described in the development plan or whether this might be regulated in another law.

Roof structures do not have their own eaves height and are usually exempt from roof pitch requirements – only rarely are special requirements for dormer roof pitches and ridge directions specified.

However, you do have to decide whether you are asking about "roof structures" or "see attached photo": e

So our primary goal is to build a bay window on the ground floor and then raise it. However, if this is not possible, the alternative is to install a dormer in the attic. As you describe it, this should then be possible since dormers do not have an eaves height.

the eaves height of subordinate components

... does not exist to my knowledge. Of course, a dormer can also have an eave in terms of a gutter, but the eaves height in the building law sense means the fictitious edge "intersection line of outer wall and roof covering", referring to the house body as such and not to individual structures.

because even if it is a bay window, it is no longer subordinate

Why do you think it is not subordinate even then?

Why do you think it is not even then?

Because the component in the photo significantly shapes the appearance of the building and also considerably increases the living space.