Here are your options while printing from Lightroom mobile(iOS):
In a single photo view, tap the Share icon at the top (it's a box with an upward arrow) and then select Share from the menu. Pick Maximum Available in the next dialog then the iOS Share sheet pops up. One of the options in the bottom is Print, but you'll need an AirPrint compatible printer of course. It doesn't give you choice of placement on the page etc. but it's better than nothing.