Self-employed artists, with an income below poverty level, are eligible for social security benefits. In Germany the benefits are called ‘Arbeitslosengeld II (Alg II)‘, also referred to as ‘Hartz IV’.
Corona-Crisis: Social Security for jobb-seekers (Arbeitslosengeld II):https://www.arbeitsagentur.de/m/corona-grundsicherung/ (german)
The minimum income for a single adult is currently 449 Euros a month. For adults living in a so-called 'Bedarfsgemeinschaft' (usually with a partner or the family) this amount is reduced to 404 Euros. Costs for housing (including heating) are covered if they are appropriate. Currently the maximum rent that is considered appropriate in Berlin is 426 Euros for a single person living in the household plus reasonable expenses for heating.
Apply at the Jobcenter
Artists who want to receive benefits need to apply at the Jobcenter of the jurisdiction they live in. Forms and information are provided on the webpage of the job centre (Arbeitsagentur): www.arbeitsagentur.de.
Unfortunately the forms are available in German only.