Do I need the SUM of All Boxes of 12 and All W-2s for HSA contributions?

It depends- are you manually entering your HSA contributions made through payroll in the HSA entry in TurboTax? If so, you shouldn't do that as you will be double-counting your contributions. ‌If you have multiple W-2s, yes, all the contributions in box 12, code W are summed together to arrive at your yearly contributions.‌ TurboTax will sum them up for you. ‌If you have multiple jobs, the yearly maximum still applies.

According to Why am I showing an excess HSA contribution?, the 2024 maximum for both employer and employee HSA contributions was as follows:

• "$4,150 if you're under 55 at the end of 2024 and are covered by an individual (self-only) HDHP;
• $8,300 if you're under 55 at the end of 2024 and are covered by a family HDHP;
• $5,150 if you're 55 or older at the end of 2024 and are covered by an individual (self-only) HDHP;
• $9,300 if you're 55 or older at the end of 2024 and are covered by a family HDHP."