I found it out:
```
override_homedir = /home/%u
```
More info:
https://man.archlinux.org/man/sssd.conf.5#NSS_configuration_options
---
There are many manual pages about sssd configuration options so I
recommend having an overview first.
Most important distinction for me was that the attributes [1] are
separated from the general options [2] even the attributes [1] can be
used in [2].
[1]
https://man.archlinux.org/man/sssd-ldap-attributes.5
[2]
https://man.archlinux.org/man/sssd.conf.5