Partial storage of Photos library to iCloud?

Hi - my Photos library is 505 Gb and growing every day - active library is stored on an external SSD connected to an iMac. Is it possible to only store a portion of my Library on iCloud? Motivation: I'd like to be able to select only a few folders destined for storage/sharing in iCloud, not all 27,000+ photos and no desire to move to the 2TB plan just to accommodate photos, majority of which I don't care to share.