What is the effect of 1000mg of vitamin c taken daily for a regular person(assuming the person doesn't have a vitamin c deficiency)?

*just a side note*
the recommended daily intake of vitamin c for men 18+ is 90mg, for women 18+ it's 75 and for pregnant women, it's 85mg)

What is the effect of vitamin C taken daily for a regular person (assuming the person does not have vitamin C deficiency)?

There is no overdose, even for drinks exceeding 10 grams per day. Indeed, ascorbic acid is eliminated in the urine when its plasma concentration reaches or exceeds 12 mg / L.
Since the body eliminates urinary surplus vitamin C, there are therefore very few adverse effects because this vitamin is not stored by the body.

Massive doses (10 times the RDA of vitamin C and up to 150 times) can sometimes lead to diarrhea, increased mobilization of bone minerals, increased clotting, elevation of Uric acid concentration, gout attack, kidney stone formation.

Pe.dometer would be the most useful to you for monitoring heart rate.