What others front end skills must I learn after HTML, CSS and Js
in the job market it seems to be required that you know at least one framework (for example you could complete the Front End Libraries Certification here in Free Code Camp to learn some front end frameworks and libraries
There are front end jobs out there that are just those 3. Typically taking design mockups and building them for a backend developer to hook up to CMS.
If you want to focus on front-end, highly recommend, as mentioned above, one of the big 3 frameworks.
React or Vue or Angular and SCSS. This is good roadmap. Take a look: