Moved into new house with Delta fixtures but even when turned to the max only lukewarm water from standalone shower and all other baths but water is very hot in all faucets. I am baffled by this. I am not certain if mineral buildup could be a cause because the house was not occupied previously but was vacant for at least 4 years.

That shower faucet has Anti-Scalding ring installed on the stem and behind the handle.

Do this: Remove handle, locate the plastic ring, remove it, toss it, reinstall handle - and you should be getting all the hot water you can get.