One thing you can do with QGIS, assuming your profile has the longitudinal distance along the profile (X) and the profile height (Y) in meters, is to open the profil as a
Delimited Text Layer , in a meter based CRS like WGS 84 / Pseudo-Mercator.
Your geometry will show up near the 0,0 coordinates (Gulf of Guinea), with the scale being respected as long as the geometry is limited to a few km in extent.
Example below uses a profile generated by the qProf plugin:
cds2d is the desired longitudinal unit,
z is the profile height
Open it as a Delimited text layer and "zoom to layer" to see it:
If needed create a path (points to path) layer to get a line. You might want to add other geometries to represent the sea level (black line with a marker every 500m in the screenshot below)/ vertical frames.
Then in the Layout manager, set whatever you need in terms of rendering and scale (1:30000 here):
With that, you have both the relative x/y scale and absolute scale handled. And playing with the Geometry generator, you can probably do some really nice things with the profile