Yes, the pet anserine bursa can become very large when it is distended with fluid in a similar way to the iliopsoas bursa or the sub-acromial sub-deltoid bursa.
As in the hip it can be a little tricky to define if it is a para-meniscal / labral cyst of a bursa that is distended.
Some helpful clues are to try and track the fluid collection to it’s source and also to check for compressibility. A bursa is generally somewhat compressible and a para-meniscal ganglion is not.
It can certainly distend large enough to reach the medial joint line.
Steve