if you're an older bro like myself
stay away from heavy squats , heavy leg ext - I mostly use a Pendulum squat nowadays
high volume, maintain tension in the areas you want to grow - use foot placement to achieve this, have strong feet too so do some calf raises - get the blood in there AS YOU TRAIN, if you are in shit shape you can't train this way because your heart is piss poor so do some cardio - but do it consistently whatever the fck is
you can really train your legs as you get older - just don't beat the hell out of yourself where you hate leg days - a lot of guys are just out of shape and pumping blood down to the lower half is a bitch and working out literally feels bad but it prob doesn't pump blood to your dick that good either