For multiple conditions on a rendered attribute, you can use AND and OR. Example: rendered="{!AND(condition_1,condition_2)}"

For multiple conditions on a rendered attribute, you can also use AND and OR. Example: rendered="{!AND(condition_1,condition_2)}"

For your case, try rendered="{!DRD_Submited && recordTypeIsPPDetect == 'Platform_Detect'}", or rendered="{!AND(DRD_Submited,recordTypeIsPPDetect == 'Platform_Detect')}".