1. Standard Deduction vs Itemized Deductions - you get to take whichever one is larger. Many deductions are limited so more people are taking the Standard Deduction now. Unless their itemized deductions are more. Itemized deductions are things like Medical, Gifts to Charity, State Income Taxes Paid, Mortgage Interest, Property Taxes, Car Registration fees, etc.
For 2021 the standard deduction amounts are:
Single 12,550 + 1,700 for 65 and over or blind (14,250)
HOH 18,800 + 1,700 for 65 and over or blind
Joint 25,100 + 1,350 for each 65 and over or blind
Married filing Separate 12,550 + 1,350 for 65 and over or blind
2. Business expenses can give you a net loss on Schedule C but that only reduces your taxable income to zero. Losses won't increase a refund. But if your taxable is zero you will get back all the withholding taken out in your W2 and 1099 income and any refundable credits you qualify for.
Never heard about getting a refund if you make less business income. Except as I said above and your self employment tax will be less.
Self Employment tax (Scheduled SE) is automatically generated if a person has $400 or more of net profit from self-employment. You pay 15.3% SE tax on 92.35% of your Net Profit (If it is greater than $400). The 15.3% self employed SE Tax is to pay both the employer part and employee part of Social Security and Medicare. So you get social security credit for it when you retire.
