Dell's specifications say it is maximum 32 GB total and both Crucial and MemoryStock agree with that. That means ideally two x 16 GB sticks = total 32 GB, but a single 32 GB stick could also work. Crucial is usually correct even when the figure exceeds Dell's specs, because Crucial tests systems and guarantees their RAM will work or they will refund. However, Crucial will guarantee compatibility only for 32 GB, so if you wish to try 64 GB then they won't guarantee that configuration.
The parts upgrade page for this laptop lists a single 32gb ram chip as an option, so does that mean it can take one in each slot for a total of 64gb?
What's the max ram for a Lattiude 3510 intel i5-10210u?