Thank you Kris for your help.
My screen and all components names are in Portuguese (see below), however let me explain what exactly I need.
I have two dates “Data de nascimento” (Brithday) and “Dia do aniversário”, both are date/time type. Annually I need to fill “Dia do aniversário” with the same day and month of “Data de nascimento” plus current Year. You are correct about startOfMonth() return and I really need the month instead of the begin of the month, however I did not find this function.
By the way I am try to run this in a Image Library.
I am also created a temporary field called “Temporario” (text tpe) to try identify what information my statement are generating.
Well let me share my screen and try to correlated the Portuguese name of component with English name.
The function CONCAT has:
concat(substring(string(formatDateTime(utcNow(),'yyyy-mm-dd')),0,4),startOfMonth(body('Obter_itens')?['Data de nascimento']),dayOfMonth(body('Obter_itens')?['Data de nascimento']))