  The efficiency of optical emitters can be dramatically enhanced by reducing
the effective mode volume (the Purcell effect). Here we predict an analogous
enhancement for electron-phonon (el-ph) scattering, achieved by compressing the
electronic Wannier orbitals. Reshaping of Wannier orbitals is a prominent
effect in graphene moir\'e superlattices (SLs) where the orbitals are tunable
by the twist angle. A reduction of the orbital effective volume leads to an
enhancement in the effective el-ph coupling strength, yielding the values
considerably bigger than those known for pristine monolayer graphene. The
enhanced coupling boosts the el-ph scattering rates, pushing them above the
values predicted from the enhanced spectral density of electronic excitations.
The enhanced phonon emission and scattering rates are manifest in the
observables such as electron-lattice cooling and the linear-$T$ resistivity,
both of which are directly tunable by the moir\'e twist angle.
