By default there is only one SSD mounting location in the CoolerMaster K281 which is in front of the PSU mounting location internally.
You can get a better idea by downloading the product manual
here and going through to
Page 05.
https://youtu.be/WZg4KQhKfZE?t=43
^ in the middle of the cases bottom panel between HDD cage and PSU mount.
In essence you can convert your 5.25" and 3.5" drive bays with an adapter to accept SSD's but they would be technically cumbersome, expensive in some locations/regions or simply not accessible to most. If we knew your budget and purchase site(s)...