I'm not sure if there are other sections of the tax code that indicate to treat withholding from other sources as if they were withholding from wages for this purpose, but the instructions for line 19 of Form 2210 say to apply all withholding in the same way:
For withheld federal income tax and excess social security or tier 1 railroad retirement tax (RRTA), you are considered to have paid one-fourth of these amounts on each payment due date unless you can show otherwise. You’ll find these amounts on the following lines.
° Form 1040 or 1040-SR, line 25d;
° Form 1040-NR, lines 25d, 25e, 25f, and 25g;
° Also, Schedule 3 (Form 1040), line 10, if you filed the above forms;
° Form 1041, Schedule G, line 14.
