How to escape the Plains?

I spawned in my first survival world in like 4 years, on PE, and no matter how far I travel from my home, I'm in the Plains. There's trees, flowers, some sand and rivers (and lakes and lakes and lakes that take me to MORE PLAINS), and there's a few hills. I've found 1 and a half villages. I had to make a compass, not because I went far but because the land was so flat I just kept wandering around nowhere, lost and low-key freaking out.
I'm making a mine under a hill at my house. Maybe if I go far enough and dig up 1000 or more blocks from my spawn? I'm not sure. It feels super liminal, and I'm kinda about to quit on the world as a whole, but I wanted this one to be a forever world. Help?

Update; I'm embarrassed to say the solution was very simple. I'm glad I came here and asked, I wouldn't have figured it out without this. I copied the world seed and made a creative copy where I wandered around and wrote down some of the other biome I could find. Some were very far away, like a mountain range with a jungle biome, or a bamboo and dark wood forest. A lot of birch forests. There is also a cherry forest biome basically on the same continent/island/land mass as my home and spawn. I really got lost once in the Plains, lost hope, and came to reddit. Thank you for the suggestions in the comments! You literally saved my forever world!