Is it possible to specify a decimal range with a phprand function?

Don't be complicated, just pick random numbers between moderately large numbers and divide them into moderately large numbers.

$long = random_int(35 * 1000000, 36 * 1000000);
var_dump($long / 1000000);

PS. random_int() is recommended for obtaining arbitrary integers. Some names are prettier than rand(), but this is more cryptographically secure.