Yellow wrote:

There is no way of getting less than the £155 unless you are missing NI
credits and SERPS (and contracting out) is simply no more.

SERPS/S2P is no more but it was a thing between 1987(?) and 2016, so it
has an effect

if you still won't believe me then please believe it from the
horse's mouth

"Your starting amount will include a deduction if you were contracted
out of the Additional State Pension"