A search for Kaluza-Klein excited vector boson resonances,
W
KK
, decaying in cascade to three
W
bosons via a scalar radion
R
,
W
KK
→
W
R
→
W
W
W
, in a final state containing two or three massive jets is presented. The search is performed with
√
s
=
13
 
 
TeV
proton-proton collision data collected by the CMS experiment at the CERN LHC during 2016–2018, corresponding to an integrated luminosity of
138
 
 
fb
−
1
. Two final states are simultaneously probed, one where the two
W
bosons produced by the
R
decay are reconstructed as separate, large-radius, massive jets, and one where they are merged into a single large-radius jet. The observed data are in agreement with the standard model expectations. Limits are set on the product of the
W
KK
resonance cross section and branching fraction to three
W
bosons in an extended warped extra-dimensional model and are the first of their kind at the LHC.