pkr wrote:
Lightweight and under $100....
That will get you a wobbly tripod that you'll hate using and probably end up breaking within a year or two.
You really need to spend more. Keep in mind, if you buy a good tripod it might last a lifetime and serve to support many different cameras you use over the years. (One of my tripods is getting close to 40 years old and has been used with a wide variety of cameras ranging from small 35mm point n shoots up to large format view cameras, and everything in between... other tripods I have are 15 to 20 years old. They weren't cheap and all still work fine.)
Look at travel tripods, such as are discussed here:
https://www.bhphotovideo.com/explora/photography/buying-guide/travel-tripodsTravel tripods tend to be the most compact and lightest weight. The better ones are well though out and reasonably steady and durable. But there are other possible problems. For best steadiness and durability, you want as few leg sections as possible (also makes a tripod faster to set up). And you want to minimize having to raise a center column to bring the camera up to a comfortable working height. The more leg sections there are, the smaller diameter the lower ones need to be in order to nest inside the next size above. Personally I use four tripods and three of them have 3-section legs. The fourth has 4-section, but is an extra tall tripod so the lowest section usually isn't needed. Two of my tripods don't even have center columns. The other that do, one is a heavy duty cross-braced, geared column (on very heavy tripod that I only use in studio). The last is on the extra tall so I almost never need to raise the column for height, instead I only use it reversed to hang camera and lens below the tripod for low-angle work such as ground level macro shots.
Unfortunately, both these consideration.... minimal center column use and fewest possible leg sections.... make for less compact and usually heavier tripod.
Plus, the lightest weight tripods are carbon fiber, which also makes them more expensive. Carbon fiber also does a better job than metal absorbing vibration. It can be more comfortable to work with in really cold or hot weather, too.
There may be others I'm unfamiliar with, but about the most affordable, lightweight model that I feel very comfortable recommending is the Benro Travel Angel. There's an aluminum version of that for $250... and a carbon fiber version that sells for $400.
The Manfroto BeFree carbon fiber tripod is pretty affordable at about $265... or the aluminum version for about $145. But I'm not a fan of flip-lever leg locks both of those use, which can all-too-easily get caught on a branch or a sleeve or cuff while using the tripod. Those types of locks also wear over time and need adjustment or replacement. My tripods use the twist-collar type leg locks, which are a little slower but are self adjusting and basically never wear out. That Manfroto also has much lower load capacity is shorter than the Benro, so won't be as stable. The ballhead included with the BeFree also uses Manfroto's proprietary quick releases, which aren't as common and versatile as than the Arca-Swiss compatible QR platform found on the Benro Travel Angel. There are sturdier Manfroto and they've even started to make some heads with Arca-compatible quick release... but those are bigger, heavier and more expensive... They also still use the flip-lever leg locks.
There's also a Davis & Sanford Traverse Carbon Fiber tripod listed at the above link, which sells for about $170. I'm not familiar with it, but it appears more similar to the Benro (height, leg locks, leg sections, quick release), except the Traverse is rated for a bit less weight.
Also, I mentioned quick releases... which are included on most tripod heads these days. The heads on above tripods with Arca-Swiss type might come with a universal plate, but I'd recommend buying one that's been custom made to fit your camera. I see L-brackets for Sony RX10IV selling on eBay and elsewhere for around $25 (and that's a bargain! L-brackets for some other cameras can cost 10X as much!). But this is in addition to the cost of the tripod itself. Many manufacturers make parts and accessories to work with the Arca-Swiss system. The way cameras and lenses using it mount also allows for some adjustment to achieve better balance than is possible with other, less widely used types of QR.
So, in the end I recommend you plan to spend more. Most people are very happy when they do.... getting a tripod that works well and will last for many years. Folks who "buy cheap", usually aren't as happy and ultimately end up spending more replacing flimsy tripods every year or two.... either when the last flimsy one broke or they got so disgusted with it they decided to get another.
Hope this helps!