There's no one-size-fits-all answer; it depends on your preference.
If you're not comfortable showing your face, consider creating a theme page. However, having a personal brand is often better because it builds trust with your audience.
Trust leads to stronger connections with followers, which is crucial for growth and earning money on Instagram.
That said, theme pages are not a bad choice. Many of them have large audiences and make a decent income, sometimes reaching 10k or more each month. Starting a theme page is easier, even though there's more competition. The challenge is gaining followers since people interact with a page, not a person.
In summary, if you're okay with showing your face, go for a personal brand. If not, a theme page works too. Both approaches have their advantages, and success is possible with either one if you put in the effort and stay committed on Instagram.