The ToughTough feat (PHB, p. 170) is exactly what you want.:
Your hit point maximum increases by an amount equal to twice your level when you gain this feat. Whenever you gain a level thereafter, your hit point maximum increases by an additional 2 hit points.
On the other threadother Q&A, plenty of people gave you advice on increasing your constitutionConstitution, which is also an option with feats, but if that's your goal, it'd be better to just use your next ASI on level upto do that directly instead of taking a feat.