If I have Frigid Jewel in my base, I draw for turn, then I play Stacked Deck and put a card in my hand from that. Would this trigger Frigid Jewel's ability of giving a unit plus 2 might?

No, using Stacked Deck will not trigger Frigid Jewel.

The Breakdown

1. Frigid Jewel's Condition: Frigid Jewel has a triggered ability that specifically activates "When you draw your second card each turn."
2. Drawing vs. Putting into Hand: In Riftbound, "drawing" a card is a distinct game action (Rule 413.1). Stacked Deck instructs you to "look at" the top three cards and "put 1 into your hand." As confirmed by RiftJudge FAQ #10462, "putting" a card into your hand does not constitute "drawing" a card.
3. The Sequence:
   • Draw Step: You perform your mandatory draw for the turn. This counts as your first card drawn.
   • Playing Stacked Deck: Even though you add a card to your hand, because it is "put" into your hand rather than "drawn," the condition for Frigid Jewel is not met.

Because Stacked Deck does not count as drawing a card, it does not advance the count toward the second card draw required to trigger Frigid Jewel.