Hello,
the logo looks good.
We do have an example snippet for changing out the icons on the Detail page, but this won’t effect listings pages or the map. The icons should be the recomended size because of the use of the category icons on the map. To see the snippet, open this link and search “Change category icons on the detail page”:
https://wpgeodirectory.com/docs/faqs/detail-page/
Kor already linked you here: https://wpgeodirectory.com/docs/faqs/where-can-i-find-map-markers/
I recommend you take a look at how those are sized, maybe download one or two.
Here is a construction icon, for example.
https://mapicons.mapsmarker.com/markers/industry/construction/
Map markers look better when they are higher contrast. You might consider making a custom google map that matches the teal color of your logo, and then make the icons YELLOW with dark , here is with #a8900a
If you need more help with those or other customizations, please contact a GD Expert https://geodirectoryexperts.com – Geotourism Center makes icon sets.