explode.php

$test = 'ACCOUNT_PERFORMANCE_REPORT (Sep 13, 2018-Sep 19, 2018)"\n
  Account,Clicks,Impressions,CTR,Conversions,Conv. rate,Cost,Avg. position,Avg. CPC,Day\n
  Massive Infinity,104,6115,1.70%,2.00,2.30%,79610000,1.2,765481,2018-09-17\n
  Massive Infinity,16,716,2.23%,0.00,0.00%,116140000,2.7,7258750,2018-09-14\n
  Massive Infinity,0,69,0.00%,0.00,0.00%,0,1.0,0,2018-09-15\n
  Massive Infinity,86,8633,1.00%,0.00,0.00%,155350000,1.2,1806395,2018-09-18\n
  Massive Infinity,91,7758,1.17%,1.00,1.28%,119260000,1.1,1310549,2018-09-19\n
  Massive Infinity,5,699,0.72%,0.00,0.00%,44850000,2.7,8970000,2018-09-13\n
  Massive Infinity,0,95,0.00%,0.00,0.00%,0,1.0,0,2018-09-16\n
  Total,302,24085,1.25%,3.00,1.12%,515210000,1.3,1705993, --\n';
dd(explode(PHP_EOL, $test));

// output

array:10 [
0 => "ACCOUNT_PERFORMANCE_REPORT (Sep 13, 2018-Sep 19, 2018)"\n"
1 => "            Account,Clicks,Impressions,CTR,Conversions,Conv. rate,Cost,Avg. position,Avg. CPC,Day\n"
2 => "            Massive Infinity,104,6115,1.70%,2.00,2.30%,79610000,1.2,765481,2018-09-17\n"
3 => "            Massive Infinity,16,716,2.23%,0.00,0.00%,116140000,2.7,7258750,2018-09-14\n"
4 => "            Massive Infinity,0,69,0.00%,0.00,0.00%,0,1.0,0,2018-09-15\n"
5 => "            Massive Infinity,86,8633,1.00%,0.00,0.00%,155350000,1.2,1806395,2018-09-18\n"
6 => "            Massive Infinity,91,7758,1.17%,1.00,1.28%,119260000,1.1,1310549,2018-09-19\n"
7 => "            Massive Infinity,5,699,0.72%,0.00,0.00%,44850000,2.7,8970000,2018-09-13\n"
8 => "            Massive Infinity,0,95,0.00%,0.00,0.00%,0,1.0,0,2018-09-16\n"
9 => "            Total,302,24085,1.25%,3.00,1.12%,515210000,1.3,1705993, --\n"
]