Not strictly, no. Much more so than the previous games though.
You progress through it linearly by means of a train which travels between environments. Some of these are large enough to function as 'open world-ish' while you're there, but there's no going between them as you please.
Metro Exodus is really good. Impressed with their take on the not actually an open world aspect.
Only real criticisms so far are the crap dialogue and voice acting, and the not very convincing AI.