First off, you must have an Snapdragon S10?S10+, mod will not work with Exynos. I used the instructions provided on this link from Reddit:
https://www.reddit.com/r/galaxys10/...even/?utm_medium=android_app&utm_source=share
Scroll down to the section I've pasted below and follow the instructions and you should be good to go. The wide-angle lens will also work. IMPORTANT: Do not open up GCam until you've extracted the Gcam.zip listed in the instructions.
For the system update ending in SBA (received on or around March 8, 2019)
S10_1_MGC_6.1.021_BSG_Arnova_TlnNeun_V1.3.030119.0645.apk by Arnova8g2 with a couple mods by me
Download this zip:
https://drive.google.com/open?id=18JIIUxxBW5f0xphVl42QL_0AIFnVruyA
Open My Files, find the Gcam.zip (probably under Internal Storage/Downloads/) then tap the GCam.zip, click Extract, then press Back, and you should see a GCam folder. Long press that, select Move, go back to Internal Storage, click Move Here
Open Google Camera, double tap the black space around the shutter button
March patch: Select S10csMar2.xml and Restore. Now when you cycle the camera switch icon you'll get the wide angle sensor eventually.