The OP asked for advice on online training courses, then clarified that he’s only interested in ESRI products. Loads of people reply saying just download QGIS which isn’t what he asked help with.
I suggest you learn some GIS basics first, before diving into ESRI. ArcMAP is like PhotoShop when you are still trying to get used to paint.
ESRI do some free training: https://www.esri.com/training/catalog/57630434851d31e02a43ef28/getting-started-with-gis/
There are a few others offering free courses:
https://www.class-central.com/mooc/5489/coursera-fundamentals-of-gis
I think it depends on what kind of GIS job and industry you are trying to get into. Try and specialise in one aspect to start with.
QGIS is way great to try and apply some of the concepts you will learn about so worth a download and it’s not that different from ArcMAP really in the same way GIMP isn’t that differant from Photoshop…