It's definitely possible, but with Duxa in particular is difficult to incorporate parts of other UIs into, or to take parts from Duxa to other UIs. I've found trying move/replace individual UI pieces usually results in the UI not loading and I end up struggling to figure out which additional files I need to also move/replace to make it actually load the UI. Anything with gauges and the spell window in particular have caused me a lot of issues.
The easiest way to get larger HP bars for both you, your target, and your group would be to just use the
Rustle UI, which has pretty large ones, but is based on the QQui rather than Duxa.