When you start working on your scene for the Web, it's better to think about composition first:
The composition of the Spline scene can be divided by "orientation" and "position".
By orientation, it can be Object-oriented and Space-oriented

When the composition is Object-oriented, you focus on the object itself.
This type of composition also can be split by the position of this object:

When the composition is space-oriented, you focus on filling the space with multiple objects.
To understand the rules of composition better, I recommend watching this tutorial: https://youtu.be/r6LPNRVhGKA?si=F1U_WK5DGm8wdOG0