Hi Sotiris,
Apple didn't start actual parts pairing on the screen until the iPhone 11, so there won't be any issue with updating the True Tone data on an iPhone X. I just replaced the screen on my granddaughter's iPhone X three weeks ago and had no issues with copying the True Tone data from the old screen to the new one. She's current on her OS updates, so it is not an issue for the X's, at least not right now.
I have the QianLi iCopy II if that matters. I understand the JC V1S works well too.
I've told my son and daughter-in-law not to upgrade their kid's phones to anything newer than the iPhone X, as the reparability drops significantly after that model. Pairing batteries and screens - the two most oft-replaced parts on a phone - to the logic board is a death knell for self repair. She says she'll get them Apple Care, which is fine if you want to pay for it, but I won't be repairing those phones.
@sotiriskonst Yes, the iPhone 11 will have pairing issues. Apple started pairing parts after the X. On the 11 if you change the battery you'll get a message that it may not be genuine and you lose your battery health indications from Settings, but the battery will work correctly. Same with the screen; you will get a non-genuine part warning and I believe you will lose True Tone.
The workaround for the battery is to cut the BMS electronics off the original battery and solder/spot weld them onto a replacement cell without the BMS. You also need something called a tag-on board that goes between the battery and the motherboard in order to reset the cycle count and health percentage.
I'm not so sure about a workaround for the display; if I recall correctly you may have to unsolder a chip from the old display and solder it onto the replacement.
On later models, starting with the iPhone 12 you can get around those issues by using Apple's self repair program, but that does mean you have to buy the parts from Apple and use/rent their equipment to do the parts replacement. Models previous to the 12 are out of luck in that department; your only option there is to pay Apple to do the replacements.