How to enter NTR route? I try to do it but I always end up on the route of exchange or love
There are 3 main routes (romance, sharing/swinging, hard NTR) with several subpaths, so there are a lot of choices, which have impact. If you want NTR no matter what, you should enable the special hardcore NTR mode at the beginning of the game. Not my cup of tea, but I looked into it for completeness.
I've played through the game any way I can imagine, but there are still locked gallery entries in the NTR Extras.
I also tried to unlock it manually, but had to give up. Either I looked in the wrong place or it's not very simple.
There are two variants of why you still have locked gallery events. One is that the scene in question is on the other wing of routes. We have a side with the various Kati/Jamal and another with the Lee/Davis routes. You have to play paths of both sides to unlock all scenes. Playing e.g. the Kati and Jamal side does not unlock the corresponding Lee/Davis stuff.
The second possibility is that you have one of the very specific events to unlock. For instance, the rooftop fun event on the romance and sharing routes has very exact prerequisites, without the needed stats and prefacing scenes done, you will not get it.
A last possibility and the one I think might be it most probably is that the scene in question is in the patron version of the game. The public version we have is 2 updates behind the patron version. The event is probably already accessible for the patrons, but on the public version only once it catches up to the current patron one.