I was wondering if UE5 can support 50k+ lines of a db/CSV as they rappresent the parameters of the whole animation. (coordinates[x,y,z], TimeDelta, Speed, Brake) Any documentation is very much appreciated
There is no existing functionality in the engine itself for this extremely specific use case. Of course, it can "support" it if you write a custom solution using the many available tools within the engine.
You can use IFileHandle to stream in a file (your csv): link
You can then parse the incoming data to create a FVector3 of your coordinates, a float of your TimeDelta, etc. For example, FVector::InitFromString may help: link
However, this depends very much on the format of your data. Parsing string/texts into values is not specific to UE4, you can find a lot of info on converting streams of binary/character data to needed values.
Applying the animation as the data is read is a separate, quite big, task. Since you provide no details on what the animation data represents, or what you need to apply it to, I cannot really help.
In general though, it can help you a lot to break down your question into 3-4 separate, more specific, questions. In any case though, this is a task that will require a lot of research and work.
And even before that, it might be good to research alternative approaches and changing the pipeline, to avoid using such non-standard file structures for animation.