Hi @PJ_Bowman98 ,
Do you want to save the timestamp in yyyy-dd-MM format submitted by the MS Form to the 'Date and time' column in the SharePoint List?
Maybe you could try the following expressions:
formatDateTime(concat(split(Dynamic Content,'/')[0],'/',split(Dynamic Content,'/')[2],'/',split(Dynamic Content,'/')[1]),'yyyy/MM/dd')
formatDateTime(concat(split(outputs('Get_response_details')?['body/r32f8311fe8c44656be4fd094ece24cf0'],'/')[0],'/',split(outputs('Get_response_details')?['body/r32f8311fe8c44656be4fd094ece24cf0'],'/')[2],'/',split(outputs('Get_response_details')?['body/r32f8311fe8c44656be4fd094ece24cf0'],'/')[1]),'yyyy/MM/dd')

Best Regards,
Charlie Choi