I found under “data protection” in LineageOS that it is possible to protect apps by a pattern.
The apps disappear after the protection and appear again only after using the pattern.
I think it is not really an encryption of the apps and only a little protection if you hand the phone e.g. to a colleague to show him your holiday photos and to avoid that he reads on this occasion your mails. Therefore the question:
Does it bring more safety if unencrypted phone is lost or stolen?
Prior to asking questions in the Forum i always look into the Fairphone - and Lineage Forum but did not find any info. Therefore, many thanks for the quick and clear answer!