  We propose to realize second-order topological superconductivity in bilayer
spin-polarized Fermi gas superfluids. We focus on systems with intralayer
chiral $p$-wave pairing and with tunable interlayer hopping and interlayer
interactions. Under appropriate circumstances, an interlayer even-parity $s$-
or $d$-wave pairing may coexist with the intralayer $p$-wave. Our model
supports localized Majorana zero modes not only at the corners of the system
geometry, but also at the terminations of certain one-dimensional defects, such
as lattice line defects and superfluid domain walls. We show how such
topological phases and the Majorana zero modes therein can be manipulated in a
multitude of ways by tuning the interlayer pairing and hopping. Generalized to
spinful systems, we further propose that the putative $p$-wave superconductor
Sr$_{2}$RuO$_{4}$, when subject to uniaxial strains, may also realize the
desired topological phase.
