Can there be a way where we can avoid getting STD even by performing unprotected sex everytime?

Condoms. The only way to minimize risk is to be in a truly monogamous relationship with a trusted partner who has been previously tested. If you have both been cleared then there is no risk (assuming no cheating). Condoms are effective in preventing stds passed via fluid transmission like gonorrhea, chlamydia & hiv. Condoms are less effective in skin to skin transmitted stds like hpv, herpes and syphilis.