Need to find a DNS command

I dont have a v12 to test it. But it should be same across all version,

Please try the below:

tmsh modify gtm pool gtm_pool_name members modify { 1.1.1.1:1_1_1_1_80 { order 1 } 2.2.2.2:2_2_2_2_80 { order 0 } }

(/Common)(tmos) list gtm pool gtm_pool_name                           
gtm pool gtm_pool_name {
    members {
        1.1.1.1:1_1_1_1_80 {
            order 0
        }
        2.2.2.2:2_2_2_2_80 {
            order 1
        }
    }
}
(/Common)(tmos) modify gtm pool gtm_pool_name members modify { 1.1.1.1:1_1_1_1_80 { order 1 } 2.2.2.2:2_2_2_2_80 { order 0 } }
(/Common)(tmos) list gtm pool gtm_pool_name
gtm pool gtm_pool_name {
members {
    1.1.1.1:1_1_1_1_80 {
        order 1
    }
    2.2.2.2:2_2_2_2_80 {
        order 0
    }
}
}