<script>
window.onload = function () {
var userAgent = navigator.userAgent || navigator.vendor || window.opera;

// eğer iossa
if (/iPad|iPhone|iPod/.test(userAgent) && !window.MSStream) {
window.location.href = "https://applelinki";
}
// android cihazsa
else if (/android/i.test(userAgent)) {
window.location.href = "https://androidlinki";
}
// ikiside değilse
else {
window.location.href = "https://siten";
}
};
</script>
bu scripti kullanabilirsin.