  In the present paper, we first establish a version of the abstract lower and
upper-solution method for our class of operators. In this sense, we
investigated the main objective of this paper, that is, the existence of a
positive solution for a new class of fractional systems of the Kirchhoff type
with $\psi$-Hilfer operators via the method of sub and supersolutions in
$\psi$-fractional space $\mathbb{H}^{\alpha,\beta;\psi}_{p}(\Omega)$
