For Digital Marketing, Udemy is the best. Then there are various skill courses available on skillshare. There are data science course and data analytics course on Upgard, which is pretty great. Would recommend to do courses from all these three sites.
Coding, digital marketing, SEO, data analysis. All these courses offer great internship opportunities. I personally have done from Internshala. You can try that or there are other sites too. Creative writing and editing is also a got option. If you like to write blogs (best )
For analysts I think so u can do projects using R,SQL,Python or SAS. These are available nowadays on coursera. If u r a CSE then u can do more competitive programming as there's no end to it or pick up some development projects.