I wasn't able to locate any written iFixit-style guides to replacing the screen on your phone, but there are YouTube videos available that show the procedure fairly well. The first one I watched was very unprofessional and would have resulted in damage to the screen being removed (although if you're replacing it, that's usually not an issue), but this one appears to be reasonably well done and includes everything you need to know.
[link|https://www.youtube.com/watch?v=eS8YYPpOanE|INFINIX SMART 6 PLUS LCD REPLACEMENT. - YouTube]
The one issue I had with this one is that when it comes to separating the LCD from the frame, the video makes it look incredibly simple, whereas it is usually stuck on much better than this one appears to be, so be aware it will probably be more difficult to get the LCD off the frame; you'll probably have to go around the screen with a thin blade or opening tool to separate the adhesive.
Otherwise, the only other comment I have is to mention that it's usually wise to test the replacement screen before gluing it down; set it in place and plug it in, then insert the battery and connect it then power on the phone and verify that the LCD and touch screen are functioning. If it's all good, then power it back down, take the battery and screen back off and proceed to follow the video.
I'm not sure what options are available for ordering replacement parts, but they appear to be readily available on places like Amazon, eBay and AliExpress among others. Here's the first one that came up on my cursory search.
[link|https://www.amazon.com/Screen-Infinix-Vision-Digitizer-Assembly/dp/B0BV8VGQH9|Amazon.com: OEM LCD Screen for Infinix Smart 6 Plus India/Itel P38 / Itel Vision 3 Plus with Digitizer Full Assembly : Cell Phones & Accessories]
Hopefully that gives you the information you need to replace your screen. Don't forget to buy glue and be sure to take lots of pictures as you work and once you're done you can use them to create your own iFixit repair guide to help out those who follow with the same problem.