Does Windows 10 LTSB 2019 have the ability to perform mbr2gpt.exe ?

One of the things you can do is build a Windows 10 bootable PE image based on 1709 or greater - Get the ADK to make this - (licensing applies here so you should consider this) and include the MBR2GPT.exe executable.  3rd party and bitlocker(its possible but..) drives are out of scope for doing this on.  If you have a machine that is MBR and you want it to be GPT boot up the 1709 PE  image and use the mbr2gpt /validate then use the mbr2gpt /convert .  While Microsoft doesn't officially support this it works great and I have done it testing a fleet conversion using SCCM.  To be officially supported, purchase a third party tool, like 1E to give you the support comfort.  After the conversion to GPT be sure to flip the BIOS to UEFI (manually or lots of powershell scripts can do this!)....