and then use one modifier with offset only in x direction and another with offset in both x and y direction.
Also, there are tons of tutorials on youtube on how to make textures tilable (e.g. in Photoshop) and also how to use them in blender, e.g. https://www.youtube.com/watch?v=-VgtSL5ZpYc
The texture itself can’t be seamless completely due to the little bits of added details. You’d either be better making the basic pattern in geometry, or editing the image to make it as close to seamless as possible in an image editor such as GIMP / Photoshop.
This is the best I could get, not ideal, some blurring in the original image and had to clone bits from elsewhere to make things join up.
make yourself with:
– Paintprograms have tools for tiled images (Krita (opensource) has even a tiled view)
– procedural generation (something like MaterialMaker (opensource))