Charging multiple (rechargable) LIR2032 (similiar to CR2032)
These are Lithium-Ion based cells and they're not that simple to charge properly. With charging properly I mean, respecting everything listed in the datasheet.

For example, when a Lithium-Ion based cell has reached 4.2 V when charging, you must stop charging.

You should not connect the cells in parallel as very large currents can flow and that will damage the cells.

When you connect them in series there is no way to stop charging one cell when it is full (has reached 4.2 V) when some other cells is not full yet.

Ideally you should have an individual charging controller (chip/module) for each cell. An example of such a charging module is the TP4056 based modules you can get cheap on Ebay. However a LIR2032 should be charged with around 35 mA which I have never tried with a TP4056, it will probably work though. At least you need to change a resistor (the resistor that sets the charging current, see the datasheet of the TP4056) on the TP4056 module. Such a module only needs 5 V input and it will stop charging the cell when it is at 4.2 V.

If you're less concerned with treating your LIR2032 cells properly you could consider the "poor man's" way of charging them:

Since we want to stop charging at 4.2 V, we need a 4.2 V supply. You will have to use a supply with an adjustable output voltage for this and set it to 4.2 V or even a bit less like 4.1 V to be safe.

If you cannot find such a supply or want to use a fixed voltage one, then I suggest getting voltage regulator module. For example an LM2596 based module with an output voltage adjustment setting (most modules have this). Then supply 7 V or more (but stay below 30 V) to the LM2596 module and set its output to 4.1 V

Then use a resistor in series with each cell to limit the current when the cell is empty. An empty cell should have about 3.5 V so the voltage drop across the resistor will be 4.1 V - 3.5 V = 0.6 V, we want 35 mA to flow so the resistor needs to be 0.6 V / 35 mA = 17 ohms. You will have a hard time finding those so use 18 ohms which are easy to find. Note that each cell needs *its own resistor** to the 4.2 V. You can charge as many cells as you like as long as the supply can deliver enough current. But 35 mA isn't a lot. Even on a 1 A supply you can charge 1 A / 35 mA = 28 cells at the same time.