In IDA I would press Alt+G and set the T register to 1 to first the code to be Thumb, but in Ghidra am not not sure how to force it.
The context is I have some functions pointed to by a data structure, I have set those to have a data type of a new function pointer type, so I am not sure if I really just need to re-analyze the code, and it will flow correctly (also not sure how to that), Or if I just need to manually force it.
[Edit:]I originally selected ARMv4 as my target, after doing some reading ARM architecture and starting again with ARMv7 the code correctly has Thumb support.