There are two options one is you can write multiple condition actions and if you dont want to use multiple condition actions, you can use set variable, and expression in set variable like below, which checks if FileName starts with FLA then variable value will be "FLA" otherwise variable value will be "NoFLA"
if(startsWith(variables('FileName'),'FLA'),'FLA','NOFLA')
This way you can use multiple set variables and use same variable across all set variable actions. Then use switch action and use that variable in switch action with different cases of value you want to check. Let me know if its unclear, example screenshots of flow added below:
Check FLA value in filename
Check ABC value in filename
Switch condition