Is $4,500 to add insulation, solar roof fans, and replace soffit vents a fair price?

I just bought my first house in Texas and my a/c is not cooling to the set temperature during the day. It has been getting up to 79 degrees and won’t get lower. The unit is brand new and has been checked twice and everything is working properly. I just don’t want to pay all that money and then it not change the cooling ability. It currently has batt insulation, but not much. The auditor also advised me to caulk around the doorframes and windows, and to replace the weatherstripping around the doors to prevent hot air coming in. I'm also wondering about air sealing things in the attic or throughout the house, and what soffit baffles are in relation to soffit vents, as I know nothing about this stuff.