See :- Quotes copied from today's news.
"Jeremy Corbyn could establish political party to rival Labour in blow to Sir Keir Starmer"
"Ex-Labour leader Jeremy Corbyn, 72, could upgrade his Peace & Justice Project Charity into a political party under plans to run on the ticket at the next election, the Telegraph claims. It is claimed Mr Corbyn is contemplating the move after privately accepting he will not be reinstated as a Labour MP, despite representing the party in the Commons".
I would suggest that there is already an existing party into which he could slot in very easily. It's called the Communist Party. No need to create a new party.