It depends.

Modern SSDs come in various types. Ones that store multiple bits per cell, do so by using multiple charge levels to represent multiple bits. Instead of one and zero, there can for instance be four different charge levels to represent 00, 01, 10, and 11, allowing a single cell to store two bits.

That makes a cell much more sensitive, since a smaller change in the charge is required to change the stored value. As opposed to an SLC cell which would simply be empty or charged depending on whether it's storing a 1 or a 0.

Good SLC nand should be able to store stuff for a decade just fine, if not longer. This is what'll be in any decent USB drive, as they're intended to spend the vast majority of their time unpowered.

QLC nand uses 16 different charge levels to store 4 bits per cell. That means a 1/16 change in charge would start corrupting data. PLC is in development, and will use 32 levels to store 5 bits. This'll be in your budget multi-terabyte SSDs.

Temperature also plays a role. The nand cells will lose charge at different rates at different temperatures.

You'll want to consult the specs of whatever drive your looking at. The variance is huge. From some drives needing a firmware level "data-refresh" that's constantly keeping the data from disappearing (people seeing bit-rot was a problem with some drives back when TLC first became common), to stuff that's fine for decades.