Hello Benoit,
C9500-48Y4C: Cisco Catalyst 9500 Series high-performance switch with 48x 1/10/25G Gigabit Ethernet + 4x 40/100G Uplink
see the datasheet
https://www.cisco.com/c/en/us/products/collateral/switches/catalyst-9500-series-switches/nb-06-cat9500-ser-data-sheet-cte-en.html
You have flexibility on the uplink optics but all you can do is to buy a second unit and to create an SVL like a VSS pair.
About FAN:
>> The switches also ship with up to five field-replaceable variable-speed fans. These have front-to-back airflow and can operate with up to one individual fan failure. The fan trays support fan-tray Online Insertion and Removal (OIR) and can support a maximum fan speed of up to 24,000 rpm.
some models support optional network modules but it shouldn't be the case of this model.
Hope to help
Giuseppe