Convert terraced house to be age-appropriate

Hello,
We live in a terraced house with a typical room layout on the ground floor (kitchen, living-dining room, guest WC).
Has anyone remodeled or used an extension to design their terraced house in such a way that one can use only the ground floor in old age? Who has tips/experiences regarding this?

Has anyone remodeled or, with the help of an extension, designed their terraced house so that you can use only the ground floor in old age? Who has tips/experiences on this?

My tip would be to rather change the property in this case. In a mid-terrace house, the extension – as far as it is even allowed there – can usually only extend into the area where the neighboring terraces are (and you usually cannot attach your own terrace to it afterward because it would then protrude from the building line). Without an extension, however, terraced house ground floors are virtually "apartments."

Has anyone done a conversion or with the help of an extension

What exactly do you want to build on? It must also be somehow approved and permitted as living space. That is at most the case in very old terraced houses, so allowed... like for example the Marienkäfersiedlung, which is a listed building in Munich. But don't despair: in most standard terraced houses, you can install a stairlift that reduces the barrier to the bedroom and bathroom.

like for example the Marienkäfersiedlung,

I correct myself: it is the Maikäfersiedlung.