I still think the operation mentioned is the solution (it’s actually more general that what OP asks for, but can me made to work for OP’s case):
>>> import tensorflow as tf
>>> v = [1, 2, 3, 4, 5,6]
>>> tf.linalg.LinearOperatorToeplitz(v, v).to_dense()
<tf.Tensor: shape=(6, 6), dtype=int32, numpy=
array([[1, 2, 3, 4, 5, 6],
       [2, 1, 2, 3, 4, 5],
       [3, 2, 1, 2, 3, 4],
       [4, 3, 2, 1, 2, 3],
       [5, 4, 3, 2, 1, 2],
       [6, 5, 4, 3, 2, 1]], dtype=int32)>