  Feedback from AGN is known to affect the host galaxy's evolution. In radio
AGN, one manifestation of feedback is seen in gas outflows. However, it is
still not well understood whether the effect of feedback evolves with the radio
AGN life cycle. In this study, we investigate this link using the radio
spectral shape as a proxy for the evolutionary stage of the AGN. We used [OIII]
emission line spectra to trace the presence of outflows on the ionised gas.
Using a sample of uniformly selected 129 radio AGN with
$L_\textrm{1.4GHz}\approx10^{23}-10^{26}$ W Hz$^{-1}$, and a mean stacking
analysis of the [OIII] profile, we conclude that the ionised gas outflow is
linked to the radio spectral shape, and it evolves with the evolution of the
radio source. We find that sources with a peak in their radio spectra
(optically thick), on average, drive a broad outflow ($FWHM\approx1330\pm418$
km s$^{-1}$) with a velocity $v_\textrm{out}\approx 240$ km s$^{-1}$. However,
we detect no outflow in the stacked [OIII] profile of sources without a peak in
their radio spectrum. In addition, we find that individual outflow detections
are kinematically more extreme in peaked than non-peaked sources. We conclude
that radio jets are most effective at driving gas outflows when young, and the
outflow is typically short lived. Our stacking analysis shows no significant
dependence of the presence of ionised gas outflows on the radio morphology, 1.4
GHz luminosity, optical luminosity and Eddington ratio of these sources. We
also identify candidate restarted AGN in our sample, whose [OIII] profiles
suggest that they have more disturbed gas kinematics than their evolved
counterparts, although the evidence for this is tentative. Our findings support
the picture where the impact of AGN feedback changes as the source evolves, and
young radio jets interact with the ambient medium, clearing a channel of gas as
they expand.
