Best microSD cards for Galaxy S9 in 2022 | Android Central
Amazon.com: SanDisk 128GB Ultra Micro SD SDXC UHS-I Class 10 works with Samsung Galaxy S9 Memory Card S9+, S9 Plus (SDSQUAR-128G-GN6MN) with Everything But Stromboli (TM) Card Reader (Class 10 128GB) :
Amazon.com: Samsung Pro Plus 256GB MicroSD Class 10 UHS-I Memory Card for Samsung Galaxy S20 FE 5G, S20 Ultra, S20, S20+, S10, S9 Phone - MB-MD256KA Bundle with Everything But Stromboli Micro
Here is the official spec sheet for the Galaxy S9 and Galaxy S9+ - SamMobile
Amazon.com: SanDisk 128GB Ultra Micro SD SDXC UHS-I Class 10 Works with Samsung Galaxy S9 Memory Card S9+, S9 Plus (SDSQUAB-128G-GN6MN) Bundle with (1) Everything But Stromboli MicroSDXC & SD Card Reader :
How to install SD and SIM card into Samsung Galaxy S9 Plus - YouTube