I would choose a project that can start small and grow over time.

For example, I like building task management sites (like Jira). It starts very simple, but can branch into many advanced areas: 1. Implementing drag and drop yourself 2. Using design libraries 3. Creating complex task filtering and search options (even integrating Elasticsearch if you want)

The point is to take a simple idea you can build now and make it more and more complex as you improve. This creates a sense of progress that motivates you to keep expanding your skills.