Looks like you need two things to change your placemark icon and increase the size of the label text (If I understand your intention correctly). First, fix your styleUrl reference, and then construct the necessary style tags.
Your current Placemark contains two <styleURL> tags, so it's probably using the second one, which references "My_Style&...
Here my solution, entirely in QGIS (version >= 3.14, for versions >= 3.0 and < 3.14, maybe few adjustments are needed).
The entry parameters of the function are :
QGIS interface iface
The solar eclipse elements, you can find it in the ...
This is a two-step solution,
Step 2: QGIS (Python). It gets the text from the clipboard, parses to obtain latitude and longitude, then adds the point to the active layer.
Open the website.
Open DevTools Ctrl+Shift+C.
Source > Snippets > New snippet &...