‘C’mon C’mon’ is a beautiful but untethered journey

“C’mon C’mon” (2021) – Writer/director Mike Mills’ last two films – “Beginners” (2010) and “20th Century Women” (2016) – look to the past. His past.  “Beginners” – starring Christopher Plummer, Ewan McGregor, and Melanie Laurent – is based on Mills’ dad.  Hal (Plummer) comes out during his golden years, and Plummer won a Best Supporting Actor Oscar for his revelatory performance.  Six years later, Mills turns to his mother with “20th Century Women”, as Annette Bening plays Dorothea, a single mom who reaches out to a 30-something (Greta Gerwig) and…