Not sure I am understanding what our asking. The putter shaft angle in relationship to the sole of the putter is the Lie angle. It can not be 90⁰. That would make a putter non-conforming by the rules of golf. There has to be at least a 10⁰ variance from vertical according to the rules of golf. Below is a link to the rules PDF on the USGA site. Page 21, 22 / Part 2 Section d on Alignment explains the rule.
You can have a shaft that is a single of double bend come out of a putter head at 90⁰, but a bend must occur at a max of 5″ up from the sole that creates the minimum 10⁰ angle required. That is on page 27 and 28.
Hope this helps.