In Islam there no such thing called 18+.

In Islam there no such thing called 18+.
Rather Allah says what it means:
Tell the believing men that they should restrain their gaze (from looking at the women whom it is lawful for them to marry, and from others’ private parts), and guard their private parts and chastity. This is what is purer for them. God is fully aware of all that they do.
قُلْ لِلْمُؤْمِنِينَ يَغُضُّوا مِنْ أَبْصَارِهِمْ وَيَحْفَظُوا فُرُوجَهُمْ ۚ ذَٰلِكَ أَزْكَىٰ لَهُمْ ۗ إِنَّ اللَّهَ خَبِيرٌ بِمَا يَصْنَعُونَ
Surat Alnoor,ayah 30
My Allah help us to lower our gaze and not to look at what's forbidden.