In 2021 Jupiter will be edge-on to the Sun and Earth (with equinox on May 2). This geometry will allow the observations of several mutual phenomena ("phemus" from phénomenes mutuelles in French) of the galilean moons (transits, and eclipses between the galilean moons) resulting in hundreds of events. These kind of events occur over a broad period of time of less than a year separated by 6 Earth years to the previous and next epochs of Phemus.
The IMCCE (Institut de mécanique céleste et de calcul des éphémérides) has initiated an observing campaign with predictions of the timings of the events available at https://www.imcce.fr/recherche/campagnes-observations/phemus/phemu#. The webpage contains information about the tips for observations of the events and tools. Detailed events can inform about the details of the orbits of the satellites and gravity effects on them improving our knowledge of the Jupiter system.
Detailed ephemerides of the events are also available at: http://nsdb.imcce.fr/multisat/nsszph517he.htm.
You can also plan your observations with visualisations of the events using WinJUPOS (Tools > Ephemerides > Graphics). John H. Rogers, from the BAA indicates that some of the events listed by IMCCE are actually behind Jupiter or in its shadow and are not observable and using WinJupos in advance can be a good idea towards a successful plannification of the observation.