add top of descent to vfr map
Calculating TOD is a basic piloting competence especially for VFR Flight while you don’t normally use too much sophisticate instrument.
That’s simple as : TOD = (Actual ALT - Destination ALT) / 1000 * 3 That gives you a Standard 3° slope distance to destination
After what you determine the Vertical Speed to respect : Descent Rate = Ground Speed * 5