Ideas for project to learn software development?

Currently 5 months out of graduating from undergrad and getting my bachelors in Electrical/Computer engineering.

Through my undergrad I did mostly embedded systems software. Creating software for microcontrollers for projects on a larger system. I developed the software for my senior design project which handled control of servo motors and interfaced with a user touch screen for control of our project. This was done in C.

Most of the software I’ve been exposed to was in C and C++ and was used for embedded systems.

I got my job in this field, and am unsatisfied. I want to start seeking a new job but want to increase my skill set so I can become more attractive to companies.

Everyone keeps saying “don’t learn a language for the sake of learning a language. Do a project so you can understand how to apply the language.”

I feel like I’ve had little exposure to what kinds of things you can create besides embedded systems.

How do I increase my software development skills? I’m uncertain what kind of software development I want to do and what kind of projects I’m capable of going. How do I get exposure and find what I want to apply myself to?

This is a broad question and I apologize but I feel stuck and hope to get some advice to steer me in the right direction.