@BillScanlan thanks for reaching out! The quick answer is yes, the Keen Targhee will be similarly sized to the Keen Newport sandals. However, with that said, it's important to remember that the fit/feel of a boot is pretty different from the fit/feel of a sandal. For example, the boots may feel tighter, simply because your foot is fully enclosed in material, and therefore may need a little more break-in period than your sandals.
Although it's hard to say exactly over the internet with seeing your foot and having you try the boots on, we'd probably recommend sizing up 1/2 size from your sandal size to account for your socks and feet swelling that often occurs during the course of a hike.
We have also begun to reopen many of our stores across the country for in-store shopping, with additional stores planning to reopen over the next 2 weeks, in case that's helpful for trying on!