There are some very light summery long sleeve shirts and dresses you could try to find!
https://www.amazon.com/dp/B07F38ZLB4/ref=cm_sw_r_cp_apa_glt_fabc_H3TF5CA0BRKJE23W2907
https://www.amazon.com/dp/B0783PKSB8/ref=cm_sw_r_cp_apa_glt_fabc_K1S52AZ8QY5R2YADD21T
Or you could wear some light long sleeve cardigans over an outfit like this
https://www.amazon.com/dp/B07MQJPWG8/ref=cm_sw_r_cp_apa_glt_fabc_RJ000C8BJJQNRDV1CA6W