Yes, in two ways. If the match's level requirement is Suggested, anyone can join. If it is Required, a player outside the level range can send a request to join, and the organiser can accept it.
Required or Suggested
When a player creates a public or private match in the app, they choose a Level requirement:
Required: only players inside the level range can join directly.
Suggested: the level range is shown as a guide, but anyone can join.
Defaults:
Public matches start as Required.
Private matches start with your club's Default level requirement for private matches (Required or Suggested).
Requests to join
If a match is Required and a player's level is outside the range, they can request to join. The match organiser can accept the request in the app.
Changing the defaults
Go to Settings → Rules & Limits.
Open the Match Settings tab.
Choose Required or Suggested in Default level requirement for private matches.
Click Save.
Good to know
On the same tab you can set how wide a level range players can choose (the level spans).
Matches you create in the calendar are always Required. To let anyone join, set the level range from 1 to 7.