Yes equilateral triangles are similar. Equilateral triangles have the same length for all 3 sides and angles. A small equilateral triangle can have the sides be 2in and a larger equilateral triangle can have sides that are 5in. The triangles would be the same, just different sizes. Think of plates. Let’s say the plates are the same, same color, shape, and make. The only different is the diameter. One plate is larger than the other. Equilateral triangles are just like that.
Hope this helped