Does relation[route=bicycle] include all ways that are cycle lanes or cycle tracks?
Edit: I wanted to know this to see if I include all bike route relations, will it give me all possible bike ways or there will still be some ways that are not mapped to a relation
No, it doesn't.
A bicycle relation includes all ways that are part of this specific cycle route. A specific relation can represent a certain local/regional/national/international cycle network, for example.
Not every cycle lane is part of a cycle network. Likewise, a cycle lane can be part of more than one network and thus be contained in more than one cycle relation. Even more, there can be cycle routes containing ways that aren't cycle lanes/tracks but just regular roads that are part of a cycle network.
This is documented for example at https://wiki.openstreetmap.org/wiki/Cycle_routes
