We use olyan before an adjective to mean "...as...as...".

Ági olyan okos, mint Einstein. Ági is as smart as Einstein.

Of course we can use nem too, to mean "not as ... as ...":

Angelina Jolie nem olyan szép, mint Ági. Angelina is not as pretty as Ági.

N.B. here, mint means as, not than. We cannot use the -nál/nél suffixes in equality statements, only in comparative. See comparative for more details of mint and -nál.