Searches for beyond the standard model Higgs bosons are presented, particularly in the context of an extended Higgs boson sector containing more than the single Higgs doublet field of the standard model such as two-Higgs-doublet models, including a search for neutral Higgs boson decays into a $\rm b\bar b$ pair and a search for a heavy pseudoscalar boson decaying to a Z boson and a Higgs boson. The data collected with the CMS detector at the LHC at centre-of-mass energy of 13 TeV is used, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. No signal above the standard model background expectation is observed. Upper limits are placed on the product of the cross section and branching fraction for each search, and interpreted in different models of an extended Higgs sector.