meaning

comparative can mean "rather" besides "more", and superlative can mean "very" besides "most", especially in Eutropius

comparative can also mean "too much"

formation

comparative

adverb

NT acc of the corresponding comparative adjective is used as the adverb.

Allen & Greenough

adjective

adjective stem + iōr + 3rd declension adjective endings

note the short o in M/F nominative singular
also note the NT forms that are sometimes different

cārus, cāra, cārum

M/FNT
nominativecāriŏrcāriōrēscāriuscāriōra
accusativecāriōremcāriōrēs, cāriōrīscāriuscāriōra
genitivecāriōriscāriōrium
dativecāriōrīcāriōribus
ablativecāriōre, cāriōrecāriōribus

levis, leve

M/FNT
nominativeleviŏrleviōrēsleviusleviōra
accusativeleviōremleviōrēs, leviōrīsleviusleviōra
genitiveleviōrisleviōrium
dativeleviōrīleviōribus
ablativeleviōre, leviōrīleviōribus

https://www.youtube.com/watch?v=G0iuSzlvQ80
https://dcc.dickinson.edu/grammar/latin/declension-comparatives