The aging process itself can cause a stiffening of the blood vessels; also our genes, etc. In general, for people with hypertension, more potassium is better. One might use a salt substitute, like "Morton's Salt Substitute", which is potassium chloride. Or drink low sodium v-8 juice, which is high in K. One might also take Magnesium citrate, or Mg-taurate supplements; according to label. One might also take a garlic supplement like Garlicin HC (TM) according to label instructions, or another good garlic supplement (e.g. Kwai). If one likes celery, this makes a good snack! And the general advice still applies: report all supplements you take to your doctor when you visit.
P.S. If a person has pre-existing kidney disease, they should consult a doctor before beginning to supplement potassium and/or magnesium.
Studies etc. K https://www.ncbi.nlm.nih.gov/m/pubmed/21403995/
Mg: https://www.ncbi.nlm.nih.gov/m/pubmed/22051430/
Celery: https://www.ncbi.nlm.nih.gov/m/pubmed/25352064/ Also: https://www.google.com/amp/s/health.clevelandclinic.org/celery-may-help-bring-your-high-blood-pressure-down/amp/ There is a lot more interesting stuff on the web about celery and other than just this. This study addresses the kidneys, high bp is not good for the kidneys over time.
Garlic: https://www.webmd.com/vitamins/ai/ingredientmono-300/garlic
There is plenty of quality material on the net regarding K, mg, celery and garlic to aid control of hypertension.
NB: Of course, those with hypertension, even mild hypertension, should be under the care of a doctor and as I said above, the doctor should be informed of the supplements one takes.