You can visualize a series of different, dissolved buffers using Geometry generator with this expression (in line 3, adapt the list of different buffers sizes):
collect_geometries (
array_foreach (
array(0.5,1,1.5,2,3,4,5),
eval (
'buffer (collect(buffer ($geometry,' ||
@element ||
')),0)'
)
)
)
Based on the point layer (red points), different buffers in different colors are created using the expression:

If you want to style each distance differently, enclose the expression in a segments_to_lines()
function (see documentation) and then use data driven override for different aspects of the style (color, stroke width etc.), based on the variable @geometry_part_num
:
