It can be done with complex profiles. And I know it has been discussed here before as I was part of one of the conversations. Try a search with complex profiles and top plates and/or studs.
As Link said, this has been discussed countless times with profiles given for beams, plates within walls, etc.
The attached image summarizes what you need to do for a beam...
1. Make a square the size of the SMALLEST timber/beam you will ever have. (Profiles can be stretched bigger, but never smaller.)
2. Use the Split command or shortcut to cut this square into four triangles. (Select square, split once from corner to corner. Now select the two resulting triangles and split from the opposite corners - you now have 4 triangles.)
3. Assign DIFFERENT fills to adjacent triangles: ArchiCAD will only show a line between fills if they are different in name/index number (appearance is irrelevant). In this case, you need two fills, indicated as "A" and "B" in the screenshot. If you need a particular fill and do not have another that looks like it, just duplicate the original and use the duplicate for 'B'.
4. Make sure that you have the Horizontal and Vertical stretch enabled and the stretch lines on the outside faces of your square as shown (default).
5. Save the profile.
When you use this profile with the beam or wall tool, the cross will show up in section. Since you have made it a stretchy profile, you can specify whatever dimensions are required for your beam and the "x" will show up properly.
PS I don't believe the (limited) START edition of ArchiCAD has this feature.
One of the forum moderators • AC 26 USA and earlier • macOS Ventura 13.2.1, iMac Pro 10-Core, Radeon Pro Vega 64